lcd: Consolidate in-viewport clipping routines

In-viewport clipping code is duplicated across 8 files, making
it a chore to change anything related to clipping; refactor the
clipping logic into dedicated functions.

Change-Id: I4ab20bb3c59b0406098d0c7d23833025f17a320a

10 files changed, 214 insertions, 948 deletions

diff --git a/firmware/drivers/lcd-16bit-common.c b/firmware/drivers/lcd-16bit-common.c
index 523354d5d2..ad41485dfe 100644
--- a/firmware/drivers/lcd-16bit-common.c
+++ b/firmware/drivers/lcd-16bit-common.c
@@ -133,31 +133,9 @@ void lcd_fillrect(int x, int y, int width, int height)
     fb_data *dst, *dst_end;
     int len, step;
 
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, NULL, NULL))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        y = 0;
-    }
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     /* drawmode and optimisation */
     if (lcd_current_viewport->drawmode & DRMODE_INVERSEVID)
     {
@@ -235,33 +213,9 @@ void ICODE_ATTR lcd_mono_bitmap_part(const unsigned char *src, int src_x,
                                      int src_y, int stride, int x, int y,
                                      int width, int height)
 {
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* convert to viewport coordinates */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     /* move starting point */
     src += stride * (src_y >> 3) + src_x;
     src_y &= 7;
@@ -465,35 +419,13 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
     fb_data *dst, *dst_row;
     unsigned dmask = 0x00000000;
     int drmode = lcd_current_viewport->drawmode;
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-         (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
         return;
+
     /* initialize blending */
     BLEND_INIT;
 
-    /* clipping */
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     /* the following drawmode combinations are possible:
      * 1) COMPLEMENT: just negates the framebuffer contents
      * 2) BG and BG+backdrop: draws _only_ background pixels with either
diff --git a/firmware/drivers/lcd-16bit-vert.c b/firmware/drivers/lcd-16bit-vert.c
index 166af02791..c721ef6302 100644
--- a/firmware/drivers/lcd-16bit-vert.c
+++ b/firmware/drivers/lcd-16bit-vert.c
@@ -54,46 +54,23 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
                                       int stride_image, int stride_src);
 
 #include "lcd-color-common.c"
-#include "lcd-16bit-common.c"
 #include "lcd-bitmap-common.c"
+#include "lcd-16bit-common.c"
 
 /*** drawing functions ***/
 
 /* Draw a horizontal line (optimised) */
 void lcd_hline(int x1, int x2, int y)
 {
-    int x;
     fb_data *dst, *dst_end;
     int stride_dst;
 
     lcd_fastpixelfunc_type *pfunc = lcd_fastpixelfuncs[lcd_current_viewport->drawmode];
 
-    /* direction flip */
-    if (x2 < x1)
-    {
-        x = x1;
-        x1 = x2;
-        x2 = x;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)y >= (unsigned)lcd_current_viewport->height) ||
-        (x1 >= lcd_current_viewport->width) ||
-        (x2 < 0))
+    if (!lcd_clip_viewport_hline(&x1, &x2, &y))
         return;
 
-    if (x1 < 0)
-        x1 = 0;
-    if (x2 >= lcd_current_viewport->width)
-        x2 = lcd_current_viewport->width-1;
-
-    /* Adjust x1 and y to viewport */
-    x1 += lcd_current_viewport->x;
-    x2 += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
-    dst = FBADDR(x1 , y );
+    dst = FBADDR(x1, y);
     stride_dst = lcd_current_viewport->buffer->stride;
     dst_end = dst + (x2 - x1) * stride_dst;
 
@@ -108,36 +85,14 @@ void lcd_hline(int x1, int x2, int y)
 /* Draw a vertical line (optimised) */
 void lcd_vline(int x, int y1, int y2)
 {
-    int y, height;
+    int height;
     unsigned bits = 0;
     enum fill_opt fillopt = OPT_NONE;
     fb_data *dst, *dst_end;
 
-    /* direction flip */
-    if (y2 < y1)
-    {
-        y = y1;
-        y1 = y2;
-        y2 = y;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)x >= (unsigned)lcd_current_viewport->width) ||
-        (y1 >= lcd_current_viewport->height) ||
-        (y2 < 0))
+    if(!lcd_clip_viewport_vline(&x, &y1, &y2))
         return;
 
-    if (y1 < 0)
-        y1 = 0;
-    if (y2 >= lcd_current_viewport->height)
-        y2 = lcd_current_viewport->height-1;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y1 += lcd_current_viewport->y;
-    y2 += lcd_current_viewport->y;
-
     height = y2 - y1 + 1;
 
     /* drawmode and optimisation */
@@ -194,33 +149,9 @@ void ICODE_ATTR lcd_bitmap_part(const fb_data *src, int src_x, int src_y,
 {
     fb_data *dst;
     int stride_dst;
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
-        return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
+        return;
 
     src += stride * src_x + src_y; /* move starting point */
     dst = FBADDR(x, y);
@@ -244,34 +175,9 @@ void ICODE_ATTR lcd_bitmap_transparent_part(const fb_data *src, int src_x,
     fb_data *dst, *dst_end;
     int stride_dst;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     src += stride * src_x + src_y; /* move starting point */
     dst = FBADDR(x, y);
     stride_dst = lcd_current_viewport->buffer->stride;
diff --git a/firmware/drivers/lcd-16bit.c b/firmware/drivers/lcd-16bit.c
index 6dff6f3b50..fd032c0956 100644
--- a/firmware/drivers/lcd-16bit.c
+++ b/firmware/drivers/lcd-16bit.c
@@ -62,36 +62,14 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
 /* Draw a horizontal line (optimised) */
 void lcd_hline(int x1, int x2, int y)
 {
-    int x, width;
+    int width;
     unsigned bits = 0;
     enum fill_opt fillopt = OPT_NONE;
     fb_data *dst, *dst_end;
 
-    /* direction flip */
-    if (x2 < x1)
-    {
-        x = x1;
-        x1 = x2;
-        x2 = x;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)y >= (unsigned)lcd_current_viewport->height) ||
-        (x1 >= lcd_current_viewport->width) ||
-        (x2 < 0))
+    if (!lcd_clip_viewport_hline(&x1, &x2, &y))
         return;
 
-    if (x1 < 0)
-        x1 = 0;
-    if (x2 >= lcd_current_viewport->width)
-        x2 = lcd_current_viewport->width-1;
-
-    /* Adjust x1 and y to viewport */
-    x1 += lcd_current_viewport->x;
-    x2 += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     width = x2 - x1 + 1;
 
     /* drawmode and optimisation */
@@ -144,37 +122,14 @@ void lcd_hline(int x1, int x2, int y)
 /* Draw a vertical line (optimised) */
 void lcd_vline(int x, int y1, int y2)
 {
-    int y;
     fb_data *dst, *dst_end;
     int stride_dst;
     lcd_fastpixelfunc_type *pfunc = lcd_fastpixelfuncs[lcd_current_viewport->drawmode];
 
-    /* direction flip */
-    if (y2 < y1)
-    {
-        y = y1;
-        y1 = y2;
-        y2 = y;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)x >= (unsigned)lcd_current_viewport->width) ||
-        (y1 >= lcd_current_viewport->height) ||
-        (y2 < 0))
+    if (!lcd_clip_viewport_vline(&x, &y1, &y2))
         return;
 
-    if (y1 < 0)
-        y1 = 0;
-    if (y2 >= lcd_current_viewport->height)
-        y2 = lcd_current_viewport->height-1;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y1 += lcd_current_viewport->y;
-    y2 += lcd_current_viewport->y;
-
-    dst = FBADDR(x , y1);
+    dst = FBADDR(x, y1);
     stride_dst = lcd_current_viewport->buffer->stride;
     dst_end = dst + (y2 - y1) * stride_dst;
 
@@ -194,34 +149,9 @@ void ICODE_ATTR lcd_bitmap_part(const fb_data *src, int src_x, int src_y,
     fb_data *dst;
     int stride_dst;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     src += stride * src_y + src_x; /* move starting point */
     dst = FBADDR(x, y);
     stride_dst = lcd_current_viewport->buffer->stride;
@@ -244,34 +174,9 @@ void ICODE_ATTR lcd_bitmap_transparent_part(const fb_data *src, int src_x,
     unsigned fg = lcd_current_viewport->fg_pattern;
     int stride_dst = lcd_current_viewport->buffer->stride;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     src += stride * src_y + src_x; /* move starting point */
     dst = FBADDR(x, y);
 
diff --git a/firmware/drivers/lcd-1bit-vert.c b/firmware/drivers/lcd-1bit-vert.c
index 49c15c041e..e1b65ca9c0 100644
--- a/firmware/drivers/lcd-1bit-vert.c
+++ b/firmware/drivers/lcd-1bit-vert.c
@@ -92,6 +92,8 @@ static void *LCDFN(frameaddress_default)(int x, int y)
     return fb->FBFN(ptr) + element;/*(element % fb->elems);*/
 }
 
+#include "lcd-bitmap-common.c"
+
 /* LCD init */
 void LCDFN(init)(void)
 {
@@ -272,10 +274,8 @@ void LCDFN(clear_viewport)(void)
 /* Set a single pixel */
 void LCDFN(drawpixel)(int x, int y)
 {
-    if (   ((unsigned)x < (unsigned)CURRENT_VP->width)
-        && ((unsigned)y < (unsigned)CURRENT_VP->height)
-        )
-        LCDFN(pixelfuncs)[CURRENT_VP->drawmode](CURRENT_VP->x + x, CURRENT_VP->y + y);
+    if (LCDFN(clip_viewport_pixel)(&x, &y))
+        LCDFN(pixelfuncs)[CURRENT_VP->drawmode](x, y);
 }
 
 /* Draw a line */
@@ -287,6 +287,7 @@ void LCDFN(drawline)(int x1, int y1, int x2, int y2)
     int d, dinc1, dinc2;
     int x, xinc1, xinc2;
     int y, yinc1, yinc2;
+    int x_vp, y_vp, w_vp, h_vp;
     LCDFN(pixelfunc_type) *pfunc = LCDFN(pixelfuncs)[CURRENT_VP->drawmode];
 
     deltax = abs(x2 - x1);
@@ -341,12 +342,15 @@ void LCDFN(drawline)(int x1, int y1, int x2, int y2)
     x = x1;
     y = y1;
 
+    x_vp = CURRENT_VP->x;
+    y_vp = CURRENT_VP->y;
+    w_vp = CURRENT_VP->width;
+    h_vp = CURRENT_VP->height;
+
     for (i = 0; i < numpixels; i++)
     {
-        if (   ((unsigned)x < (unsigned)CURRENT_VP->width)
-            && ((unsigned)y < (unsigned)CURRENT_VP->height)
-            )
-            pfunc(CURRENT_VP->x + x, CURRENT_VP->y + y);
+        if (x >= 0 && y >= 0 && x < w_vp && y < h_vp)
+            pfunc(x + x_vp, y + y_vp);
 
         if (d < 0)
         {
@@ -366,35 +370,14 @@ void LCDFN(drawline)(int x1, int y1, int x2, int y2)
 /* Draw a horizontal line (optimised) */
 void LCDFN(hline)(int x1, int x2, int y)
 {
-    int x, width;
+    int width;
     unsigned char *dst, *dst_end;
     unsigned mask;
     LCDFN(blockfunc_type) *bfunc;
 
-    /* direction flip */
-    if (x2 < x1)
-    {
-        x = x1;
-        x1 = x2;
-        x2 = x;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)y >= (unsigned)CURRENT_VP->height) || (x1 >= CURRENT_VP->width)
-        || (x2 < 0))
+    if (!LCDFN(clip_viewport_hline)(&x1, &x2, &y))
         return;
 
-    if (x1 < 0)
-        x1 = 0;
-    if (x2 >= CURRENT_VP->width)
-        x2 = CURRENT_VP->width-1;
-
-    /* adjust to viewport */
-    x1 += CURRENT_VP->x;
-    x2 += CURRENT_VP->x;
-    y += CURRENT_VP->y;
-
     width = x2 - x1 + 1;
 
     bfunc = LCDFN(blockfuncs)[CURRENT_VP->drawmode];
@@ -416,30 +399,9 @@ void LCDFN(vline)(int x, int y1, int y2)
     unsigned mask, mask_bottom;
     LCDFN(blockfunc_type) *bfunc;
 
-    /* direction flip */
-    if (y2 < y1)
-    {
-        ny = y1;
-        y1 = y2;
-        y2 = ny;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)x >= (unsigned)CURRENT_VP->width) || (y1 >= CURRENT_VP->height)
-        || (y2 < 0))
+    if (!LCDFN(clip_viewport_vline)(&x, &y1, &y2))
         return;
 
-    if (y1 < 0)
-        y1 = 0;
-    if (y2 >= CURRENT_VP->height)
-        y2 = CURRENT_VP->height-1;
-
-    /* adjust for viewport */
-    y1 += CURRENT_VP->y;
-    y2 += CURRENT_VP->y;
-    x += CURRENT_VP->x;
-
     bfunc = LCDFN(blockfuncs)[CURRENT_VP->drawmode];
     dst   = LCDFB(x,y1>>3);
     ny    = y2 - (y1 & ~7);
@@ -483,31 +445,9 @@ void LCDFN(fillrect)(int x, int y, int width, int height)
     LCDFN(blockfunc_type) *bfunc;
     bool fillopt = false;
 
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= CURRENT_VP->width)
-        || (y >= CURRENT_VP->height) || (x + width <= 0) || (y + height <= 0))
+    if (!LCDFN(clip_viewport_rect)(&x, &y, &width, &height, NULL, NULL))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        y = 0;
-    }
-    if (x + width > CURRENT_VP->width)
-        width = CURRENT_VP->width - x;
-    if (y + height > CURRENT_VP->height)
-        height = CURRENT_VP->height - y;
-
-    /* adjust for viewport */
-    x += CURRENT_VP->x;
-    y += CURRENT_VP->y;
-
     if (CURRENT_VP->drawmode & DRMODE_INVERSEVID)
     {
         if (CURRENT_VP->drawmode & DRMODE_BG)
@@ -582,34 +522,9 @@ void ICODE_ATTR LCDFN(bitmap_part)(const unsigned char *src, int src_x,
     unsigned mask, mask_bottom;
     LCDFN(blockfunc_type) *bfunc;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= CURRENT_VP->width)
-        || (y >= CURRENT_VP->height) || (x + width <= 0) || (y + height <= 0))
+    if (!LCDFN(clip_viewport_rect)(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    /* clip image in viewport */
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-    if (x + width > CURRENT_VP->width)
-        width = CURRENT_VP->width - x;
-    if (y + height > CURRENT_VP->height)
-        height = CURRENT_VP->height - y;
-
-    /* adjust for viewport */
-    x += CURRENT_VP->x;
-    y += CURRENT_VP->y;
-
     src    += stride * (src_y >> 3) + src_x; /* move starting point */
     src_y  &= 7;
     y      -= src_y;
@@ -696,5 +611,3 @@ void LCDFN(bitmap)(const unsigned char *src, int x, int y, int width,
 {
     LCDFN(bitmap_part)(src, 0, 0, width, x, y, width, height);
 }
-
-#include "lcd-bitmap-common.c"
diff --git a/firmware/drivers/lcd-24bit.c b/firmware/drivers/lcd-24bit.c
index 279ed5924a..d95415e957 100644
--- a/firmware/drivers/lcd-24bit.c
+++ b/firmware/drivers/lcd-24bit.c
@@ -173,31 +173,9 @@ void lcd_fillrect(int x, int y, int width, int height)
     fb_data bits;
     memset(&bits, 0, sizeof(fb_data));
 
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, NULL, NULL))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        y = 0;
-    }
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     /* drawmode and optimisation */
     if (lcd_current_viewport->drawmode & DRMODE_INVERSEVID)
     {
@@ -287,33 +265,9 @@ void ICODE_ATTR lcd_mono_bitmap_part(const unsigned char *src, int src_x,
     int drmode = lcd_current_viewport->drawmode;
     int row;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     src += stride * (src_y >> 3) + src_x; /* move starting point */
     src_y  &= 7;
     src_end = src + width;
@@ -491,32 +445,9 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
     fb_data *dst, *dst_row;
     unsigned dmask = 0x00000000;
     int drmode = lcd_current_viewport->drawmode;
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-         (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
-        return;
 
-    /* clipping */
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
+        return;
 
     /* the following drawmode combinations are possible:
      * 1) COMPLEMENT: just negates the framebuffer contents
@@ -758,38 +689,16 @@ static void ICODE_ATTR lcd_alpha_bitmap_part_mix(const fb_data* image,
 /* Draw a horizontal line (optimised) */
 void lcd_hline(int x1, int x2, int y)
 {
-    int x, width;
+    int width;
     fb_data *dst, *dst_end;
     lcd_fastpixelfunc_type *pfunc = lcd_fastpixelfuncs[lcd_current_viewport->drawmode];
 
-    /* direction flip */
-    if (x2 < x1)
-    {
-        x = x1;
-        x1 = x2;
-        x2 = x;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)y >= (unsigned)lcd_current_viewport->height) ||
-        (x1 >= lcd_current_viewport->width) ||
-        (x2 < 0))
+    if (!lcd_clip_viewport_hline(&x1, &x2, &y))
         return;
 
-    if (x1 < 0)
-        x1 = 0;
-    if (x2 >= lcd_current_viewport->width)
-        x2 = lcd_current_viewport->width-1;
-
-    /* Adjust x1 and y to viewport */
-    x1 += lcd_current_viewport->x;
-    x2 += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     width = x2 - x1 + 1;
 
-    dst = FBADDR(x1 , y);
+    dst = FBADDR(x1, y);
     dst_end = dst + width;
     do
     {
@@ -801,36 +710,13 @@ void lcd_hline(int x1, int x2, int y)
 /* Draw a vertical line (optimised) */
 void lcd_vline(int x, int y1, int y2)
 {
-    int y;
     fb_data *dst, *dst_end;
     lcd_fastpixelfunc_type *pfunc = lcd_fastpixelfuncs[lcd_current_viewport->drawmode];
 
-    /* direction flip */
-    if (y2 < y1)
-    {
-        y = y1;
-        y1 = y2;
-        y2 = y;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)x >= (unsigned)lcd_current_viewport->width) ||
-        (y1 >= lcd_current_viewport->height) ||
-        (y2 < 0))
+    if (!lcd_clip_viewport_vline(&x, &y1, &y2))
         return;
 
-    if (y1 < 0)
-        y1 = 0;
-    if (y2 >= lcd_current_viewport->height)
-        y2 = lcd_current_viewport->height-1;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y1 += lcd_current_viewport->y;
-    y2 += lcd_current_viewport->y;
-
-    dst = FBADDR(x , y1);
+    dst = FBADDR(x, y1);
     dst_end = dst + (y2 - y1) * LCD_WIDTH;
 
     do
@@ -848,34 +734,9 @@ void ICODE_ATTR lcd_bitmap_part(const fb_data *src, int src_x, int src_y,
 {
     fb_data *dst;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     src += stride * src_y + src_x; /* move starting point */
     dst = FBADDR(x, y);
 
@@ -896,34 +757,9 @@ void ICODE_ATTR lcd_bitmap_transparent_part(const fb_data *src, int src_x,
     fb_data *dst;
     fb_data fg, transparent, replacewithfg;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     src += stride * src_y + src_x; /* move starting point */
     dst = FBADDR(x, y);
 
diff --git a/firmware/drivers/lcd-2bit-horz.c b/firmware/drivers/lcd-2bit-horz.c
index 1bc489247c..37125679ad 100644
--- a/firmware/drivers/lcd-2bit-horz.c
+++ b/firmware/drivers/lcd-2bit-horz.c
@@ -89,6 +89,8 @@ static void *lcd_frameaddress_default(int x, int y)
     return fb->fb_ptr + element;/*(element % fb->elems);*/
 }
 
+#include "lcd-bitmap-common.c"
+
 /* LCD init */
 void lcd_init(void)
 {
@@ -418,10 +420,8 @@ void lcd_clear_viewport(void)
 /* Set a single pixel */
 void lcd_drawpixel(int x, int y)
 {
-    if (   ((unsigned)x < (unsigned)lcd_current_viewport->width)
-        && ((unsigned)y < (unsigned)lcd_current_viewport->height)
-        )
-        lcd_pixelfuncs[lcd_current_viewport->drawmode](lcd_current_viewport->x + x, lcd_current_viewport->y + y);
+    if (lcd_clip_viewport_pixel(&x, &y))
+        lcd_pixelfuncs[lcd_current_viewport->drawmode](x, y);
 }
 
 /* Draw a line */
@@ -433,6 +433,7 @@ void lcd_drawline(int x1, int y1, int x2, int y2)
     int d, dinc1, dinc2;
     int x, xinc1, xinc2;
     int y, yinc1, yinc2;
+    int x_vp, y_vp, w_vp, h_vp;
     lcd_pixelfunc_type *pfunc = lcd_pixelfuncs[lcd_current_viewport->drawmode];
 
     deltay = abs(y2 - y1);
@@ -487,12 +488,15 @@ void lcd_drawline(int x1, int y1, int x2, int y2)
     x = x1;
     y = y1;
 
+    x_vp = lcd_current_viewport->x;
+    y_vp = lcd_current_viewport->y;
+    w_vp = lcd_current_viewport->width;
+    h_vp = lcd_current_viewport->height;
+
     for (i = 0; i < numpixels; i++)
     {
-        if (   ((unsigned)x < (unsigned)lcd_current_viewport->width)
-            && ((unsigned)y < (unsigned)lcd_current_viewport->height)
-            )
-            pfunc(lcd_current_viewport->x + x, lcd_current_viewport->y + y);
+        if (x >= 0 && y >= 0 && x < w_vp && y < h_vp)
+            pfunc(x + x_vp, y + y_vp);
 
         if (d < 0)
         {
@@ -517,30 +521,9 @@ void lcd_hline(int x1, int x2, int y)
     unsigned mask, mask_right;
     lcd_blockfunc_type *bfunc;
 
-    /* direction flip */
-    if (x2 < x1)
-    {
-        nx = x1;
-        x1 = x2;
-        x2 = nx;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)y >= (unsigned)lcd_current_viewport->height) || (x1 >= lcd_current_viewport->width)
-        || (x2 < 0))
+    if (!lcd_clip_viewport_hline(&x1, &x2, &y))
         return;
 
-    if (x1 < 0)
-        x1 = 0;
-    if (x2 >= lcd_current_viewport->width)
-        x2 = lcd_current_viewport->width-1;
-
-    /* adjust to viewport */
-    x1 += lcd_current_viewport->x;
-    x2 += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     bfunc = lcd_blockfuncs[lcd_current_viewport->drawmode];
     dst   = FBADDR(x1>>2,y);
     nx    = x2 - (x1 & ~3);
@@ -559,36 +542,14 @@ void lcd_hline(int x1, int x2, int y)
 /* Draw a vertical line (optimised) */
 void lcd_vline(int x, int y1, int y2)
 {
-    int y;
     unsigned char *dst, *dst_end;
     int stride_dst;
     unsigned mask;
     lcd_blockfunc_type *bfunc;
 
-    /* direction flip */
-    if (y2 < y1)
-    {
-        y = y1;
-        y1 = y2;
-        y2 = y;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)x >= (unsigned)lcd_current_viewport->width) || (y1 >= lcd_current_viewport->height)
-        || (y2 < 0))
+    if (!lcd_clip_viewport_vline(&x, &y1, &y2))
         return;
 
-    if (y1 < 0)
-        y1 = 0;
-    if (y2 >= lcd_current_viewport->height)
-        y2 = lcd_current_viewport->height-1;
-
-    /* adjust for viewport */
-    y1 += lcd_current_viewport->y;
-    y2 += lcd_current_viewport->y;
-    x += lcd_current_viewport->x;
-
     bfunc = lcd_blockfuncs[lcd_current_viewport->drawmode];
     dst   = FBADDR(x>>2,y1);
     stride_dst = LCD_FBSTRIDE(lcd_current_viewport->buffer->stride, 0);
@@ -627,31 +588,9 @@ void lcd_fillrect(int x, int y, int width, int height)
     unsigned mask, mask_right;
     lcd_blockfunc_type *bfunc;
 
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) || (y >= lcd_current_viewport->height)
-        || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, NULL, NULL))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        y = 0;
-    }
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     bfunc      = lcd_blockfuncs[lcd_current_viewport->drawmode];
     dst        = FBADDR(x>>2,y);
     stride_dst = LCD_FBSTRIDE(lcd_current_viewport->buffer->stride, 0);
@@ -706,32 +645,9 @@ void ICODE_ATTR lcd_mono_bitmap_part(const unsigned char *src, int src_x,
     unsigned dst_mask;
     int drmode = lcd_current_viewport->drawmode;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    x += lcd_current_viewport->x;          /* adjust for viewport */
-    y += lcd_current_viewport->y;          /* adjust for viewport */
-
     src += stride * (src_y >> 3) + src_x; /* move starting point */
     src_y  &= 7;
     src_end = src + width;
@@ -894,33 +810,9 @@ void ICODE_ATTR lcd_bitmap_part(const unsigned char *src, int src_x,
     int stride_dst;
     unsigned mask, mask_right;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     stride = LCD_FBSTRIDE(stride, 0); /* convert to no. of bytes */
 
     src   += stride * src_y + (src_x >> 2); /* move starting point */
@@ -971,5 +863,3 @@ void lcd_bitmap(const unsigned char *src, int x, int y, int width, int height)
 {
     lcd_bitmap_part(src, 0, 0, width, x, y, width, height);
 }
-
-#include "lcd-bitmap-common.c"
diff --git a/firmware/drivers/lcd-2bit-vert.c b/firmware/drivers/lcd-2bit-vert.c
index b206a2d816..5fd86c409a 100644
--- a/firmware/drivers/lcd-2bit-vert.c
+++ b/firmware/drivers/lcd-2bit-vert.c
@@ -91,6 +91,8 @@ static void *lcd_frameaddress_default(int x, int y)
     return fb->fb_ptr + element; /*(element % fb->elems);*/
 }
 
+#include "lcd-bitmap-common.c"
+
 /* LCD init */
 void lcd_init(void)
 {
@@ -420,10 +422,8 @@ void lcd_clear_viewport(void)
 /* Set a single pixel */
 void lcd_drawpixel(int x, int y)
 {
-    if (   ((unsigned)x < (unsigned)lcd_current_viewport->width)
-        && ((unsigned)y < (unsigned)lcd_current_viewport->height)
-        )
-        lcd_pixelfuncs[lcd_current_viewport->drawmode](lcd_current_viewport->x + x, lcd_current_viewport->y + y);
+    if (lcd_clip_viewport_pixel(&x, &y))
+        lcd_pixelfuncs[lcd_current_viewport->drawmode](x, y);
 }
 
 /* Draw a line */
@@ -435,6 +435,7 @@ void lcd_drawline(int x1, int y1, int x2, int y2)
     int d, dinc1, dinc2;
     int x, xinc1, xinc2;
     int y, yinc1, yinc2;
+    int x_vp, y_vp, w_vp, h_vp;
     lcd_pixelfunc_type *pfunc = lcd_pixelfuncs[lcd_current_viewport->drawmode];
 
     deltax = abs(x2 - x1);
@@ -489,12 +490,15 @@ void lcd_drawline(int x1, int y1, int x2, int y2)
     x = x1;
     y = y1;
 
+    x_vp = lcd_current_viewport->x;
+    y_vp = lcd_current_viewport->y;
+    w_vp = lcd_current_viewport->width;
+    h_vp = lcd_current_viewport->height;
+
     for (i = 0; i < numpixels; i++)
     {
-        if (   ((unsigned)x < (unsigned)lcd_current_viewport->width)
-            && ((unsigned)y < (unsigned)lcd_current_viewport->height)
-            )
-            pfunc(lcd_current_viewport->x + x, lcd_current_viewport->y + y);
+        if (x >= 0 && y >= 0 && x < w_vp && y < h_vp)
+            pfunc(x + x_vp, y + y_vp);
 
         if (d < 0)
         {
@@ -514,36 +518,14 @@ void lcd_drawline(int x1, int y1, int x2, int y2)
 /* Draw a horizontal line (optimised) */
 void lcd_hline(int x1, int x2, int y)
 {
-    int x;
     int width;
     fb_data *dst, *dst_end;
     unsigned mask;
     lcd_blockfunc_type *bfunc;
 
-    /* direction flip */
-    if (x2 < x1)
-    {
-        x = x1;
-        x1 = x2;
-        x2 = x;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)y >= (unsigned)lcd_current_viewport->height) || (x1 >= lcd_current_viewport->width)
-        || (x2 < 0))
+    if (!lcd_clip_viewport_hline(&x1, &x2, &y))
         return;
 
-    if (x1 < 0)
-        x1 = 0;
-    if (x2 >= lcd_current_viewport->width)
-        x2 = lcd_current_viewport->width-1;
-
-    /* adjust x1 and y to viewport */
-    x1 += lcd_current_viewport->x;
-    x2 += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     width = x2 - x1 + 1;
 
     bfunc = lcd_blockfuncs[lcd_current_viewport->drawmode];
@@ -565,30 +547,9 @@ void lcd_vline(int x, int y1, int y2)
     unsigned mask, mask_bottom;
     lcd_blockfunc_type *bfunc;
 
-    /* direction flip */
-    if (y2 < y1)
-    {
-        ny = y1;
-        y1 = y2;
-        y2 = ny;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)x >= (unsigned)lcd_current_viewport->width) || (y1 >= lcd_current_viewport->height)
-        || (y2 < 0))
+    if (!lcd_clip_viewport_vline(&x, &y1, &y2))
         return;
 
-    if (y1 < 0)
-        y1 = 0;
-    if (y2 >= lcd_current_viewport->height)
-        y2 = lcd_current_viewport->height-1;
-
-    /* adjust for viewport */
-    y1 += lcd_current_viewport->y;
-    y2 += lcd_current_viewport->y;
-    x += lcd_current_viewport->x;
-
     bfunc = lcd_blockfuncs[lcd_current_viewport->drawmode];
     dst   = FBADDR(x,y1>>2);
     stride_dst = lcd_current_viewport->buffer->stride;
@@ -632,31 +593,9 @@ void lcd_fillrect(int x, int y, int width, int height)
     lcd_blockfunc_type *bfunc;
     bool fillopt = false;
 
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width)
-        || (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, NULL, NULL))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        y = 0;
-    }
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     if (lcd_current_viewport->drawmode & DRMODE_INVERSEVID)
     {
         if ((lcd_current_viewport->drawmode & DRMODE_BG) && !lcd_backdrop)
@@ -732,33 +671,9 @@ void ICODE_ATTR lcd_mono_bitmap_part(const unsigned char *src, int src_x,
     unsigned mask, mask_bottom;
     lcd_blockfunc_type *bfunc;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width) ||
-        (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     src    += stride * (src_y >> 3) + src_x; /* move starting point */
     src_y  &= 7;
     y      -= src_y;
@@ -905,33 +820,9 @@ void ICODE_ATTR lcd_bitmap_part(const fb_data *src, int src_x, int src_y,
     int stride_dst;
     unsigned mask, mask_bottom;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= lcd_current_viewport->width)
-        || (y >= lcd_current_viewport->height) || (x + width <= 0) || (y + height <= 0))
+    if (!lcd_clip_viewport_rect(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-    if (x + width > lcd_current_viewport->width)
-        width = lcd_current_viewport->width - x;
-    if (y + height > lcd_current_viewport->height)
-        height = lcd_current_viewport->height - y;
-
-    /* adjust for viewport */
-    x += lcd_current_viewport->x;
-    y += lcd_current_viewport->y;
-
     src   += stride * (src_y >> 2) + src_x; /* move starting point */
     src_y &= 3;
     y     -= src_y;
@@ -1014,5 +905,3 @@ void lcd_bitmap(const fb_data *src, int x, int y, int width, int height)
 {
     lcd_bitmap_part(src, 0, 0, width, x, y, width, height);
 }
-
-#include "lcd-bitmap-common.c"
diff --git a/firmware/drivers/lcd-2bit-vi.c b/firmware/drivers/lcd-2bit-vi.c
index 0580705a05..b19fdba266 100644
--- a/firmware/drivers/lcd-2bit-vi.c
+++ b/firmware/drivers/lcd-2bit-vi.c
@@ -103,6 +103,8 @@ static void *LCDFN(frameaddress_default)(int x, int y)
     return fb->FBFN(ptr) + element;/*(element % fb->elems);*/
 }
 
+#include "lcd-bitmap-common.c"
+
 /* LCD init */
 void LCDFN(init)(void)
 {
@@ -453,10 +455,8 @@ void LCDFN(clear_viewport)(void)
 /* Set a single pixel */
 void LCDFN(drawpixel)(int x, int y)
 {
-    if (   ((unsigned)x < (unsigned)CURRENT_VP->width)
-        && ((unsigned)y < (unsigned)CURRENT_VP->height)
-        )
-        LCDFN(pixelfuncs)[CURRENT_VP->drawmode](CURRENT_VP->x+x, CURRENT_VP->y+y);
+    if (LCDFN(clip_viewport_pixel)(&x, &y))
+        LCDFN(pixelfuncs)[CURRENT_VP->drawmode](x, y);
 }
 
 /* Draw a line */
@@ -468,6 +468,7 @@ void LCDFN(drawline)(int x1, int y1, int x2, int y2)
     int d, dinc1, dinc2;
     int x, xinc1, xinc2;
     int y, yinc1, yinc2;
+    int x_vp, y_vp, w_vp, h_vp;
     LCDFN(pixelfunc_type) *pfunc = LCDFN(pixelfuncs)[CURRENT_VP->drawmode];
 
     deltax = abs(x2 - x1);
@@ -522,12 +523,15 @@ void LCDFN(drawline)(int x1, int y1, int x2, int y2)
     x = x1;
     y = y1;
 
+    x_vp = CURRENT_VP->x;
+    y_vp = CURRENT_VP->y;
+    w_vp = CURRENT_VP->width;
+    h_vp = CURRENT_VP->height;
+
     for (i = 0; i < numpixels; i++)
     {
-        if (   ((unsigned)x < (unsigned)CURRENT_VP->width)
-            && ((unsigned)y < (unsigned)CURRENT_VP->height)
-            )
-            pfunc(CURRENT_VP->x + x, CURRENT_VP->y + y);
+        if (x >= 0 && y >= 0 && x < w_vp && y < h_vp)
+            pfunc(x + x_vp, y + y_vp);
 
         if (d < 0)
         {
@@ -547,36 +551,14 @@ void LCDFN(drawline)(int x1, int y1, int x2, int y2)
 /* Draw a horizontal line (optimised) */
 void LCDFN(hline)(int x1, int x2, int y)
 {
-    int x;
     int width;
     FBFN(data) *dst, *dst_end;
     unsigned mask;
     LCDFN(blockfunc_type) *bfunc;
 
-    /* direction flip */
-    if (x2 < x1)
-    {
-        x = x1;
-        x1 = x2;
-        x2 = x;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)y >= (unsigned)CURRENT_VP->height) || (x1 >= CURRENT_VP->width)
-        || (x2 < 0))
+    if (!LCDFN(clip_viewport_hline)(&x1, &x2, &y))
         return;
 
-    if (x1 < 0)
-        x1 = 0;
-    if (x2 >= CURRENT_VP->width)
-        x2 = CURRENT_VP->width-1;
-
-    /* adjust x1 and y to viewport */
-    x1 += CURRENT_VP->x;
-    x2 += CURRENT_VP->x;
-    y += CURRENT_VP->y;
-
     width = x2 - x1 + 1;
 
     bfunc = LCDFN(blockfuncs)[CURRENT_VP->drawmode];
@@ -598,30 +580,9 @@ void LCDFN(vline)(int x, int y1, int y2)
     unsigned mask, mask_bottom;
     LCDFN(blockfunc_type) *bfunc;
 
-    /* direction flip */
-    if (y2 < y1)
-    {
-        ny = y1;
-        y1 = y2;
-        y2 = ny;
-    }
-
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if (((unsigned)x >= (unsigned)CURRENT_VP->width) || (y1 >= CURRENT_VP->height)
-        || (y2 < 0))
+    if (!LCDFN(clip_viewport_vline)(&x, &y1, &y2))
         return;
 
-    if (y1 < 0)
-        y1 = 0;
-    if (y2 >= CURRENT_VP->height)
-        y2 = CURRENT_VP->height-1;
-
-    /* adjust for viewport */
-    y1 += CURRENT_VP->y;
-    y2 += CURRENT_VP->y;
-    x += CURRENT_VP->x;
-
     bfunc = LCDFN(blockfuncs)[CURRENT_VP->drawmode];
     dst   = LCDFB(x,y1>>3);
     stride_dst = CURRENT_VP->buffer->stride;
@@ -667,31 +628,9 @@ void LCDFN(fillrect)(int x, int y, int width, int height)
     LCDFN(blockfunc_type) *bfunc;
     bool fillopt = false;
 
-    /******************** In viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= CURRENT_VP->width)
-        || (y >= CURRENT_VP->height) || (x + width <= 0) || (y + height <= 0))
+    if (!LCDFN(clip_viewport_rect)(&x, &y, &width, &height, NULL, NULL))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        y = 0;
-    }
-    if (x + width > CURRENT_VP->width)
-        width = CURRENT_VP->width - x;
-    if (y + height > CURRENT_VP->height)
-        height = CURRENT_VP->height - y;
-
-    /* adjust for viewport */
-    x += CURRENT_VP->x;
-    y += CURRENT_VP->y;
-
     if (CURRENT_VP->drawmode & DRMODE_INVERSEVID)
     {
         if ((CURRENT_VP->drawmode & DRMODE_BG) && !backdrop)
@@ -769,33 +708,9 @@ void ICODE_ATTR LCDFN(mono_bitmap_part)(const unsigned char *src, int src_x,
     unsigned data, mask, mask_bottom;
     LCDFN(blockfunc_type) *bfunc;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= CURRENT_VP->width) ||
-        (y >= CURRENT_VP->height) || (x + width <= 0) || (y + height <= 0))
+    if (!LCDFN(clip_viewport_rect)(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-    if (x + width > CURRENT_VP->width)
-        width = CURRENT_VP->width - x;
-    if (y + height > CURRENT_VP->height)
-        height = CURRENT_VP->height - y;
-
-    /* adjust for viewport */
-    x += CURRENT_VP->x;
-    y += CURRENT_VP->y;
-
     src    += stride * (src_y >> 3) + src_x; /* move starting point */
     src_y  &= 7;
     y      -= src_y;
@@ -913,33 +828,9 @@ void ICODE_ATTR LCDFN(bitmap_part)(const FBFN(data) *src, int src_x,
     int stride_dst;
     unsigned mask, mask_bottom;
 
-    /******************** Image in viewport clipping **********************/
-    /* nothing to draw? */
-    if ((width <= 0) || (height <= 0) || (x >= CURRENT_VP->width)
-        || (y >= CURRENT_VP->height) || (x + width <= 0) || (y + height <= 0))
+    if (!LCDFN(clip_viewport_rect)(&x, &y, &width, &height, &src_x, &src_y))
         return;
 
-    if (x < 0)
-    {
-        width += x;
-        src_x -= x;
-        x = 0;
-    }
-    if (y < 0)
-    {
-        height += y;
-        src_y -= y;
-        y = 0;
-    }
-    if (x + width > CURRENT_VP->width)
-        width = CURRENT_VP->width - x;
-    if (y + height > CURRENT_VP->height)
-        height = CURRENT_VP->height - y;
-
-    /* adjust for viewport */
-    x += CURRENT_VP->x;
-    y += CURRENT_VP->y;
-
     src   += stride * (src_y >> 3) + src_x; /* move starting point */
     src_y &= 7;
     y     -= src_y;
@@ -1036,5 +927,3 @@ void LCDFN(bitmap)(const FBFN(data) *src, int x, int y, int width, int height)
 {
     LCDFN(bitmap_part)(src, 0, 0, width, x, y, width, height);
 }
-
-#include "lcd-bitmap-common.c"
diff --git a/firmware/drivers/lcd-bitmap-common.c b/firmware/drivers/lcd-bitmap-common.c
index 24b302b6d4..c867b214b5 100644
--- a/firmware/drivers/lcd-bitmap-common.c
+++ b/firmware/drivers/lcd-bitmap-common.c
@@ -53,6 +53,116 @@
 extern void viewport_set_buffer(struct viewport *vp,
                                 struct frame_buffer_t *buffer,
                                 const enum screen_type screen); /* viewport.c */
+
+/*
+ * In-viewport clipping functions:
+ *
+ * These clip a primitive (pixel, line, rect) given in
+ * viewport-relative coordinates to the current viewport,
+ * and translate it to screen coordinates. They return
+ * false if the resulting primitive would be off-screen.
+ */
+
+static bool LCDFN(clip_viewport_pixel)(int *x, int *y)
+{
+    struct viewport *vp = LCDFN(current_viewport);
+
+    if(*x >= vp->width || *y >= vp->height)
+        return false;
+
+    *x += vp->x;
+    *y += vp->y;
+    return true;
+}
+
+static bool LCDFN(clip_viewport_hline)(int *x1, int *x2, int *y)
+{
+    struct viewport *vp = LCDFN(current_viewport);
+
+    if (*y < 0 || *y > vp->height)
+        return false;
+
+    if (*x2 < *x1) {
+        int tmp = *x2;
+        *x2 = *x1;
+        *x1 = tmp;
+    }
+
+    if (*x1 < 0)
+        *x1 = 0;
+    else if (*x1 >= vp->width)
+        return false;
+
+    if (*x2 < 0)
+        return false;
+    else if (*x2 >= vp->width)
+        *x2 = vp->width - 1;
+
+    *x1 += vp->x;
+    *x2 += vp->x;
+    *y += vp->y;
+    return true;
+}
+
+static bool LCDFN(clip_viewport_vline)(int *x, int *y1, int *y2)
+{
+    struct viewport *vp = LCDFN(current_viewport);
+
+    if (*x < 0 || *x > vp->width)
+        return false;
+
+    if (*y2 < *y1) {
+        int tmp = *y2;
+        *y2 = *y1;
+        *y1 = tmp;
+    }
+
+    if (*y1 < 0)
+        *y1 = 0;
+    else if (*y1 >= vp->height)
+        return false;
+
+    if (*y2 < 0)
+        return false;
+    else if (*y2 >= vp->height)
+        *y2 = vp->height - 1;
+
+    *x += vp->x;
+    *y1 += vp->y;
+    *y2 += vp->y;
+    return true;
+}
+
+static bool LCDFN(clip_viewport_rect)(int *x, int *y, int *width, int *height,
+                                      int *src_x, int *src_y)
+{
+    struct viewport *vp = LCDFN(current_viewport);
+
+    if (*x < 0) {
+        *width += *x;
+        if (src_x)
+            *src_x -= *x;
+        *x = 0;
+    }
+
+    if (*y < 0) {
+        *height += *y;
+        if (src_y)
+            *src_y -= *y;
+        *y = 0;
+    }
+
+    if (*x + *width > vp->width)
+        *width = vp->width - *x;
+
+    if (*y + *height > vp->height)
+        *height = vp->height - *y;
+
+    *x += vp->x;
+    *y += vp->y;
+    return *width > 0 && *height > 0;
+}
+
 /*
  * draws the borders of the current viewport
  **/
diff --git a/firmware/drivers/lcd-color-common.c b/firmware/drivers/lcd-color-common.c
index 72ce7c209f..8a9ef64cea 100644
--- a/firmware/drivers/lcd-color-common.c
+++ b/firmware/drivers/lcd-color-common.c
@@ -40,6 +40,7 @@ static fb_data lcd_static_framebuffer[LCD_FBHEIGHT][LCD_FBWIDTH]
     IRAM_LCDFRAMEBUFFER CACHEALIGN_AT_LEAST_ATTR(16);
 
 static void *lcd_frameaddress_default(int x, int y);
+static bool lcd_clip_viewport_pixel(int *x, int *y);
 
 static fb_data* lcd_backdrop = NULL;
 static long lcd_backdrop_offset IDATA_ATTR = 0;
@@ -196,10 +197,8 @@ fb_data* lcd_get_backdrop(void)
 /* Set a single pixel */
 void lcd_drawpixel(int x, int y)
 {
-    if (   ((unsigned)x < (unsigned)lcd_current_viewport->width)
-        && ((unsigned)y < (unsigned)lcd_current_viewport->height)
-        )
-        lcd_fastpixelfuncs[lcd_current_viewport->drawmode](FBADDR(lcd_current_viewport->x+x, lcd_current_viewport->y+y));
+    if (lcd_clip_viewport_pixel(&x, &y))
+        lcd_fastpixelfuncs[lcd_current_viewport->drawmode](FBADDR(x, y));
 }
 
 /* Draw a line */
@@ -274,11 +273,8 @@ void lcd_drawline(int x1, int y1, int x2, int y2)
 
     for (i = 0; i < numpixels; i++)
     {
-        if ((x >= 0 && y >= 0)
-            && (x < w_vp)
-            && (y < h_vp)
-            )
-            pfunc(fbaddr( x + x_vp, y + y_vp));
+        if (x >= 0 && y >= 0 && x < w_vp && y < h_vp)
+            pfunc(fbaddr(x + x_vp, y + y_vp));
 
         if (d < 0)
         {
@@ -401,7 +397,7 @@ void lcd_gradient_fillrect_part(int x, int y, int width, int height,
     x1 = x;
     x2 = x + width;
 
-    if (height == 0) return;
+    if (height <= 0) return;
 
     step_mul = (1 << 16) / src_height;
     int h_r = RGB_UNPACK_RED(start_rgb);