Android APP界面黑白化处理

Android页面置灰

方案1. Android页面绘制流程一般分为measurelayoutdraw,页面置灰在draw方法中实现。draw方法参数有canvaspaintcanvas是界面的画布,paint是绘制界面的画笔。可以通过更改paint的属性更改界面背景颜色,通过设置颜色过滤器更改画笔的色调、饱和度和亮度。置灰效果饱和度为0,画笔的设置代码:

Paint  paint = new  Paint();
ColorMatrix cm = new  ColorMatrix();
cm.setStaturation(0);
paint.setColorFilter(new ColorMatrixColorFilter(cm));

方案2. 考虑性能使用HardwareLayer(GPU内部的Buffer)对绘制的图形进行缓存。设置方法setLayerType()强制View创建自己对应的层,并将自己绘制到层上。

方案3.Activity的顶层View设置置灰,实现全局置灰效果。获取界面的根View

//java
View view  = activity. getWindow(). getDecorView();
 Paint paint = new  Paint();
ColorMatrix cm = new  ColorMatrix();
cm.setStaturation(0);
paint.setColorFilter(new ColorMatrixColorFilter(cm));
view. setLayerType(View.LAYER_TYPE_HARDWARE, paint);
//kotlin
val view: View = window.decorView
val paint = Paint()
val cm = ColorMatrix()
cm.setSaturation(0f)
paint.colorFilter = ColorMatrixColorFilter(cm)
view.setLayerType(View.LAYER_TYPE_HARDWARE, paint)

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