以编程方式绘制 Android Gradient
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Android Gradient drawable programmatically
提问by marbarfa
I have a gradient drawable defined in xml that I use it as a background, like this:
我在 xml 中定义了一个渐变可绘制对象，我将其用作背景，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>
I need to implement this programmatically. I have tried to use a GradientDrawable as follows (this method is implemented on a custom view):
我需要以编程方式实现这一点。我尝试使用 GradientDrawable 如下（此方法是在自定义视图上实现的）：
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);
The problem is that it seems that setting the bounds is useless or doesn't work the same way as (android:top, android:bottom xml parameters). The resulting background is each layer painted from top to bottom, one above the other.
问题是，设置边界似乎没有用或与 (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一层，一层在另一层之上。
I want to generate something like this: 
我想生成这样的东西：
采纳答案by marbarfa
Found the answer!. Possible duplicate Multi-gradient shapes.
找到答案了！。可能重复的多渐变形状。
Replaced:
替换：
backColor.setBounds(0, 0,0, 4);
shadow.setBounds(0,98, 0, 0);
for
为了
layerList.setLayerInset(0, 0, 0, 0, 4);
layerList.setLayerInset(1, 0, 98, 0, 0);
