[Android自定义控件]带加载进度条的ImageView

public class LoadingImgView extends ImageView{

private float per;

private boolean isfinished = false;

private String colorStr;

private Paint paintLayer;
private Paint textPaint;

private Rect textbound;

private float layer_w;
private float layer_h;

public LoadingImgView(Context context) {
super(context);
init();
}

public LoadingImgView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}

public LoadingImgView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}

//初始化画笔
private void init(){
paintLayer = new Paint();
paintLayer.setColor(Color.LTGRAY);
paintLayer.setAlpha(100);
textPaint = new Paint();
textPaint.setColor(Color.DKGRAY);
textPaint.setTextSize(25);
textbound = new Rect();
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (isfinished)
return;
String perStr = (int) (per*100) + "%";
//获取文字区域的矩形大小，以便确定文字正中间的位置
textPaint.getTextBounds(perStr,0, perStr.length(),textbound);
layer_w = getWidth();
layer_h = getHeight()*per;
float y = getHeight() - layer_h;
//画遮蔽层
canvas.drawRect(0,y,layer_w,getHeight(),paintLayer);
//画文字
canvas.drawText(perStr, getWidth() / 2 - textbound.width() / 2, getHeight() / 2 + textbound.height() / 2, textPaint);
}

public void setPer(float per){
this.per = per;
//在主线程刷新
postInvalidate();
}

public void finish(){
isfinished = true;
postInvalidate();
}

}