[Android开发] SlidingMenu侧滑剩余的位置添加阴影淡入淡出

一、效果图

二、修改方法

1. 在SlidingMenu添加一个设置透明度方法

public void setOffsetFadeDegree(float f) {
mViewBehind.setOffsetFadeDegree(f);
}

2. CustomViewBehind 添加变量和方法

private float mOffsetFadeDegree;

public void setOffsetFadeDegree(float degree) {
if (degree > 1.0f || degree < 0.0f)
throw new IllegalStateException("The offsetFadeDegree must be between 0.0f and 1.0f");
mOffsetFadeDegree = degree;
}

/**
* 绘制剩余View的淡出淡入
* @param content 主界面
* @param canvas  画布
* @param openPercent 打开了的百分比
*/
public void drawOffsetFade(View content, Canvas canvas, float openPercent) {
if (mWidthOffset <= 0 || mOffsetFadeDegree <= 0) return;   //不开启就返回，不设置 淡入淡出效果

final int alpha = (int) (mOffsetFadeDegree * 255 * Math.abs(openPercent));
mFadePaint.setColor(Color.argb(alpha, 0, 0, 0));
canvas.drawRect(content.getLeft(), 0,content.getRight(), getHeight(), mFadePaint);
}

3. 最后在CustomViewAbove 的dispatchDraw 绘制view 里面调用drawOffsetFade

/**
* 绘制ui
* @param canvas
*/
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
// Draw the margin drawable if needed.
mViewBehind.drawShadow(mContent, canvas);
mViewBehind.drawFade(mContent, canvas, getPercentOpen());    //绘制剩余View的淡入淡出
mViewBehind.drawOffsetFade(mContent, canvas, getPercentOpen());
mViewBehind.drawSelector(mContent, canvas, getPercentOpen());   //
}

三、使用方法

menu.setOffsetFadeDegree(0.4f);