Conversion between Android images, bitmap, drawable, res resource images

① res resource picture is the resource picture placed under the project res file

② for Bitmap bitmap, the suffix of general file is BMP, and encoder coding is required, such as rgb565, rgb8888, etc. A pixel by pixel display object has high execution efficiency, but obvious disadvantages and low storage efficiency.

③ drawable, a general graphic object, can load commonly used images, GIF, PNG, JPG, also supports BMP, and provides some advanced visual objects, such as gradient, graphics, etc.

① put the pictures into the RES / drawable folder. The pictures in this folder belong to res resource pictures

② define image processing as a tool class, which is convenient to use or not.

③ click the button to obtain the picture and display it.

[tip] canvas is required to draw when converting drawable to bitmap. Set the size of the drawing and the boundary of the drawing.

[prompt] you can see that there is no picture set in ImageView

[prompt] for convenience, I have written a button here. Four methods cooperate with each other, and the three forms are transformed into each other