Drawable简单使用

Android文档这样定义Drawable的：

A Drawable is a general abstraction for "something that can be drawn." Most often you will deal with Drawable as the type of resource retrieved for drawing things to the screen; the Drawable class provides a generic API for dealing with an underlying visual resource that may take a variety of forms. Unlike a View, a Drawable does not have any facility to receive events or otherwise interact with the user.

 

Drawable就是一个可画的对象，其可能是一张位图（BitmapDrawable），也可能是一个图形（ShapeDrawable），还有可能是一个图层（LayerDrawable），我们根据画图的需求，创建相应的可画对象，就可以将这个可画对象当作一块“画布（Canvas）”，在其上面操作可画对象，并最终将这种可画对象显示在画布上，有点类似于“内存画布“。

 

下面的一个自定义View显示了ShapeDrawable的一些简单使用方式：

public class TestView extends View { private ShapeDrawable mShapeDrawable; public TestView(Context context) { super(context); int x = 10, y = 10; int width = 300, height = 50; mShapeDrawable = new ShapeDrawable(new OvalShape()); //ShapeDrawable.getPaint():Returns the Paint used to draw the shape mShapeDrawable.getPaint().setColor(Color.YELLOW); mShapeDrawable.setBounds(x, y, x+width, y+height); } @Override protected void onDraw(Canvas canvas) { // TODO Auto-generated method stub super.onDraw(canvas); canvas.drawColor(Color.WHITE); mShapeDrawable.draw(canvas); } }

 

程序运行效果如下图：