Android Gradient可编程绘制

时间:2012-09-14 14:57:35

标签: android background drawable

我在xml中定义了一个渐变drawable,我将它用作背景,如下所示:

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
   <item android:bottom="4dp">
      <shape>
         <gradient
            android:startColor="@color/blue"
            android:endColor="@color/dark_blue"
            android:angle="270" />
      </shape>
   </item>
   <item android:top="98dp">
      <shape>
         <gradient
            android:startColor="@color/black"
            android:endColor="@color/transparent_black"
            android:angle="270" />
      </shape>
   </item>
</layer-list>

我需要以编程方式实现此功能。我尝试使用GradientDrawable如下(此方法在自定义视图上实现):

int[] colors1 = {getResources().getColor(R.color.black), getResources().getColor(R.color.trasparent_black)};

GradientDrawable shadow = new GradientDrawable(Orientation.TOP_BOTTOM, colors1);
shadow.setBounds(0,98, 0, 0);

int[] colors = new int[2];
colors[0] = getResources().getColor(R.color.blue);
colors[1] = getResources().getColor(R.color.dark_blue);

GradientDrawable backColor = new GradientDrawable(Orientation.TOP_BOTTOM, colors);

backColor.setBounds(0, 0,0, 4);

//finally create a layer list and set them as background.    
Drawable[] layers = new Drawable[2];
layers[0] = backColor;
layers[1] = shadow;

LayerDrawable layerList = new LayerDrawable(layers);
setBackgroundDrawable(layerList);

问题是,设置边界似乎没用或者与(android:top,android:bottom xml参数)的工作方式不同。生成的背景是从上到下绘制的每个图层,一个在另一个之上。

我想生成这样的内容:IMG http://i49.tinypic.com/2nueqf.png

1 个答案:

答案 0 :(得分:9)

找到了答案!可能重复Multi-gradient shapes

替换:

backColor.setBounds(0, 0,0, 4);
shadow.setBounds(0,98, 0, 0);

layerList.setLayerInset(0, 0, 0, 0, 4);
layerList.setLayerInset(1, 0, 98, 0, 0);