拖动开始时我尝试增加图像的阴影
我创建了自定义dragshadowbuilder并增加了两倍的大小,但没有任何事情发生.
我创建了自定义dragshadowbuilder并增加了两倍的大小,但没有任何事情发生.
public class ImageDragShadowBuilder extends View.DragShadowBuilder {
public ImageDragShadowBuilder(View v) {
super(v);
}
@Override
public void onProvideShadowMetrics(Point shadowSize,Point touchPoint) {
shadowSize.set(getView().getWidth()*2,getView().getHeight()*2);
touchPoint.set(getView().getWidth() / 2,getView().getHeight() / 2);
}}
是什么原因？
解决方法
嗯,这在文档中并不是那么清楚.我正在使用给定的构建器来减小大小,你只需要通过乘以你的条件来改变除法;
private static class MyDragShadowBuilder extends View.DragShadowBuilder {
private Point mScaleFactor;
// Defines the constructor for myDragShadowBuilder
public MyDragShadowBuilder(View v) {
// Stores the View parameter passed to myDragShadowBuilder.
super(v);
}
// Defines a callback that sends the drag shadow dimensions and touch point back to the
// system.
@Override
public void onProvideShadowMetrics (Point size,Point touch) {
// Defines local variables
int width;
int height;
// Sets the width of the shadow to half the width of the original View
width = getView().getWidth() / 2;
// Sets the height of the shadow to half the height of the original View
height = getView().getHeight() / 2;
// Sets the size parameter's width and height values. These get back to the system
// through the size parameter.
size.set(width,height);
// Sets size parameter to member that will be used for scaling shadow image.
mScaleFactor = size;
// Sets the touch point's position to be in the middle of the drag shadow
touch.set(width / 2,height / 2);
}
@Override
public void onDrawShadow(Canvas canvas) {
// Draws the ColorDrawable in the Canvas passed in from the system.
canvas.scale(mScaleFactor.x/(float)getView().getWidth(),mScaleFactor.y/(float)getView().getHeight());
getView().draw(canvas);
}
}
