Added bitmap.blit function for copying slices of bitmaps

Author: Margaret Matocha

shared-bindings/displayio/Bitmap.c

@@ -172,7 +172,66 @@ STATIC mp_obj_t bitmap_subscr(mp_obj_t self_in, mp_obj_t index_obj, mp_obj_t val
     return mp_const_none;
 }
 
-//|     def fill(self, value: int) -> None:
+//|     def blit(self, x: int, y: int, source_bitmap: bitmap, x1: int, y1: int, x2: int, y2:int) -> Any:
+//|         """Inserts the source_bitmap region defined by rectangular boundaries
+//|         (x1,y1) and (x2,y2) into the bitmap at the specified (x,y) location.
+//|         :param int x: Horizontal pixel location in bitmap where source_bitmap upper-left
+//|             corner will be placed
+//|         :param int y: Vertical pixel location in bitmap where source_bitmap upper-left
+//|             corner will be placed
+//|         :param bitmap source_bitmap: Source bitmap that contains the graphical region to be copied
+//|         : param x1: Minimum x-value for rectangular bounding box to be copied from the source bitmap
+//|         : param y1: Minimum y-value for rectangular bounding box to be copied from the source bitmap
+//|         : param x2: Maximum x-value for rectangular bounding box to be copied from the source bitmap
+//|         : param y2: Maximum y-value for rectangular bounding box to be copied from the source bitmap
+//|         
+//|         ...
+//|
+
+STATIC mp_obj_t displayio_bitmap_obj_blit(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args){
+
+    // Consider improving the input checking.
+
+    displayio_bitmap_t *self = MP_OBJ_TO_PTR(pos_args[0]);
+    int16_t x = mp_obj_get_int(pos_args[1]);
+    int16_t y = mp_obj_get_int(pos_args[2]);
+    displayio_bitmap_t *source = MP_OBJ_TO_PTR(pos_args[3]);    
+    int16_t x1 = mp_obj_get_int(pos_args[4]);
+    int16_t y1 = mp_obj_get_int(pos_args[5]);
+    int16_t x2 = mp_obj_get_int(pos_args[6]);
+    int16_t y2 = mp_obj_get_int(pos_args[7]);
+
+    if ( (x<0) || (y<0) || (x > self-> width) || (y > self->height) ) {
+            mp_raise_ValueError(translate("(x,y): out of range of target bitmap"));
+    }
+    if ( (x1 < 0) || (x1 > source->width)  || 
+        (y1 < 0) || (y1 > source->height) || 
+        (x2 < 0) || (x2 > source->width)  ||
+        (y2 < 0) || (y2 > source->height) ) {
+            mp_raise_ValueError(translate("(x1,y1) or (x2,y2): out of range of source bitmap"));
+    }
+    
+    // Ensure x1 < x2 and y1 < y2
+    if (x1 > x2) {
+        int16_t temp=x2;
+        x2=x1;
+        x1=temp;
+    }
+    if (y1 > y2) {
+        int16_t temp=y2;
+        y2=y1;
+        y1=temp;
+    }
+
+    common_hal_displayio_bitmap_blit(self, x, y, source, x1, y1, x2, y2);
+
+    return mp_const_none;
+}
+
+MP_DEFINE_CONST_FUN_OBJ_KW(displayio_bitmap_blit_obj, 8, displayio_bitmap_obj_blit);
+// requires 8 parameters
+
+//|     def fill(self, value: Any) -> Any:
 //|         """Fills the bitmap with the supplied palette index value."""
 //|         ...
 //|
@@ -192,6 +251,7 @@ MP_DEFINE_CONST_FUN_OBJ_2(displayio_bitmap_fill_obj, displayio_bitmap_obj_fill);
 STATIC const mp_rom_map_elem_t displayio_bitmap_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_height), MP_ROM_PTR(&displayio_bitmap_height_obj) },
     { MP_ROM_QSTR(MP_QSTR_width), MP_ROM_PTR(&displayio_bitmap_width_obj) },
+    { MP_ROM_QSTR(MP_QSTR_blit), MP_ROM_PTR(&displayio_bitmap_blit_obj) },
     { MP_ROM_QSTR(MP_QSTR_fill), MP_ROM_PTR(&displayio_bitmap_fill_obj) },
 
 };

shared-bindings/displayio/Bitmap.h

@@ -40,6 +40,8 @@ uint16_t common_hal_displayio_bitmap_get_height(displayio_bitmap_t *self);
 uint16_t common_hal_displayio_bitmap_get_width(displayio_bitmap_t *self);
 uint32_t common_hal_displayio_bitmap_get_bits_per_value(displayio_bitmap_t *self);
 void common_hal_displayio_bitmap_set_pixel(displayio_bitmap_t *bitmap, int16_t x, int16_t y, uint32_t value);
+void common_hal_displayio_bitmap_blit(displayio_bitmap_t *self, int16_t x, int16_t y, displayio_bitmap_t *source,  
+                                        int16_t x1, int16_t y1, int16_t x2, int16_t y2);
 uint32_t common_hal_displayio_bitmap_get_pixel(displayio_bitmap_t *bitmap, int16_t x, int16_t y);
 void common_hal_displayio_bitmap_fill(displayio_bitmap_t *bitmap, uint32_t value);
 

shared-module/displayio/Bitmap.c

@@ -105,6 +105,37 @@ uint32_t common_hal_displayio_bitmap_get_pixel(displayio_bitmap_t *self, int16_t
     return 0;
 }
 
+void common_hal_displayio_bitmap_blit(displayio_bitmap_t *self, int16_t x, int16_t y, displayio_bitmap_t *source,  
+                                        int16_t x1, int16_t y1, int16_t x2, int16_t y2) {
+    // Copy complete "source" bitmap into "self" bitmap at location x,y in the "self"
+    // Add a boolean to determine if all values are copied, or only if non-zero
+    // Default is copy all values, but for text glyphs this should copy only non-zero values
+
+    if (self->read_only) {
+        mp_raise_RuntimeError(translate("Read-only object"));
+    }
+
+    // If this value is encountered in the source bitmap, it will not be copied (for text glyphs)
+    // This should be added as an optional parameter, and if it is `None`, then all pixels are copied
+    uint32_t skip_value=0;
+
+    // simplest version - use internal functions for get/set pixels
+    for (uint16_t i=0; i<= (x2-x1) ; i++) {
+        if ( (x+i >= 0) && (x+i < self->width) ) {
+            for (uint16_t j=0; j<= (y2-y1) ; j++){
+                if ((y+j >= 0) && (y+j < self->height) ) {
+                    uint32_t value = common_hal_displayio_bitmap_get_pixel(source, x1+i, y1+j);
+                    if ( (value != skip_value) ) { 
+                            common_hal_displayio_bitmap_set_pixel(self, x+i, y+j, value);
+                    }
+                }
+            }
+        }
+    }
+   
+}
+
+
 void common_hal_displayio_bitmap_set_pixel(displayio_bitmap_t *self, int16_t x, int16_t y, uint32_t value) {
     if (self->read_only) {
         mp_raise_RuntimeError(translate("Read-only object"));