BitmapLayer

Layer that displays a bitmap image. More...

Collaboration diagram for BitmapLayer:

Typedefs
typedef struct BitmapLayer	BitmapLayer

Functions
BitmapLayer *	bitmap_layer_create (GRect frame)
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)
const GBitmap *	bitmap_layer_get_bitmap (BitmapLayer *bitmap_layer)
void	bitmap_layer_set_bitmap (BitmapLayer *bitmap_layer, const GBitmap *bitmap)
void	bitmap_layer_set_alignment (BitmapLayer *bitmap_layer, GAlign alignment)
void	bitmap_layer_set_background_color (BitmapLayer *bitmap_layer, GColor color)
void	bitmap_layer_set_compositing_mode (BitmapLayer *bitmap_layer, GCompOp mode)

Detailed Description

Layer that displays a bitmap image.

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.

Function Documentation

bitmap_layer_create()

BitmapLayer* bitmap_layer_create

(

GRect

frame

)

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

• Bitmap: NULL (none)
• Background color: GColorClear
• Compositing mode: GCompOpAssign
• Clips: true

  Returns

  A pointer to the BitmapLayer. NULL if the BitmapLayer could not be created

bitmap_layer_get_bitmap()

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

bitmap_layer_get_layer()

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.

bitmap_layer_set_alignment()

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.

The bitmap layer is automatically marked dirty after this operation.

Parameters

bitmap_layer	The BitmapLayer for which to set the aligment
alignment	The new alignment for the image inside the BitmapLayer

bitmap_layer_set_background_color()

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.

The bitmap layer is automatically marked dirty after this operation.

Parameters

bitmap_layer	The BitmapLayer for which to set the background color
color	The new GColor to set the background to

bitmap_layer_set_bitmap()

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.

The bitmap layer is automatically marked dirty after this operation.

Parameters

bitmap_layer	The BitmapLayer for which to set the bitmap image
bitmap	The new GBitmap to set onto the BitmapLayer

bitmap_layer_set_compositing_mode()

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.

The compositing mode only affects the drawing of the bitmap and not the drawing of the background color.

For Aplite, there is no notion of "transparency" in the graphics system. However, the effect of transparency can be created by masking and using compositing modes.

For Basalt, when drawing GBitmap images, GCompOpSet will be required to apply any transparency.

The bitmap layer is automatically marked dirty after this operation.

Parameters

bitmap_layer	The BitmapLayer for which to set the compositing mode
mode	The compositing mode to set

See also

See GCompOp for visual examples of the different compositing modes.