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BitmapLayer ​

BitmapLayer is a Layer subtype that draws a GBitmap within its frame. It uses an alignment property to specify how to position the bitmap image within its frame. Optionally, when the background color is not GColorClear, it draws a solid background color behind the bitmap image, filling areas of the frame that are not covered by the bitmap image. Lastly, using the compositing mode property of the BitmapLayer, determines the way the bitmap image is drawn on top of what is underneath it (either the background color, or the layers beneath it).

Inside the Implementation ​

The implementation of BitmapLayer is fairly straightforward and relies heavily on the functionality as exposed by the core drawing functions (see Drawing Primitives). BitmapLayer's drawing callback uses graphics_draw_bitmap_in_rect() to perform the actual drawing of the GBitmap. It uses grect_align() to perform the layout of the image and it uses graphics_fill_rect() to draw the background plane.

Functions ​

BitmapLayer * bitmap_layer_create(GRect frame)

Creates a new bitmap layer on the heap and initalizes it the default values.

void bitmap_layer_destroy(BitmapLayer *bitmap_layer)

Destroys a window previously created by bitmap_layer_create.

Layer * bitmap_layer_get_layer(const BitmapLayer *bitmap_layer)

Gets the "root" Layer of the bitmap layer, which is the parent for the sub- layers used for its implementation.

Parameters ​
  • bitmap_layer: Pointer to the BitmapLayer for which to get the "root" Layer
Returns ​

The "root" Layer of the bitmap layer.

const GBitmap * bitmap_layer_get_bitmap(BitmapLayer *bitmap_layer)

Gets the pointer to the bitmap image that the BitmapLayer is using.

Parameters ​
  • bitmap_layer: The BitmapLayer for which to get the bitmap image
Returns ​

A pointer to the bitmap image that the BitmapLayer is using

void bitmap_layer_set_bitmap(BitmapLayer *bitmap_layer, const GBitmap *bitmap)

Sets the bitmap onto the BitmapLayer. The bitmap is set by reference (no deep copy), thus the caller of this function has to make sure the bitmap is kept in memory.

Parameters ​
  • bitmap_layer: The BitmapLayer for which to set the bitmap image
  • bitmap: The new GBitmap to set onto the BitmapLayer

void bitmap_layer_set_alignment(BitmapLayer *bitmap_layer, GAlign alignment)

Sets the alignment of the image to draw with in frame of the BitmapLayer. The aligment parameter specifies which edges of the bitmap should overlap with the frame of the BitmapLayer. If the bitmap is smaller than the frame of the BitmapLayer, the background is filled with the background color.

Parameters ​
  • bitmap_layer: The BitmapLayer for which to set the aligment
  • alignment: The new alignment for the image inside the BitmapLayer

void bitmap_layer_set_background_color(BitmapLayer *bitmap_layer, GColor color)

Sets the background color of bounding box that will be drawn behind the image of the BitmapLayer.

Parameters ​
  • bitmap_layer: The BitmapLayer for which to set the background color
  • color: The new GColor to set the background to

void bitmap_layer_set_compositing_mode(BitmapLayer *bitmap_layer, GCompOp mode)

Sets the compositing mode of how the bitmap image is composited onto the BitmapLayer's background plane, or how it is composited onto what has been drawn beneath the BitmapLayer.

Parameters ​
  • bitmap_layer: The BitmapLayer for which to set the compositing mode
  • mode: The compositing mode to set

Typedefs ​

typedef struct BitmapLayer BitmapLayer