Android - 如何以编程方式定义ShapeDrawables？

Question

我想要实现的是使用一个包含几个图层的可绘制对象，但在运行时控制一些值，比如渐变的起始颜色。这是我在my_layered_shape.xml中拥有的：

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
  <item>
    <shape android:shape="rectangle">
      <stroke android:width="1dp" android:color="#FF000000" />
      <solid android:color="#FFFFFFFF" />
    </shape>
  </item>
  <item android:top="1dp" android:bottom="1dp"> 
    <shape android:shape="rectangle">
    <stroke android:width="1dp" android:color="#FF000000" />
    <gradient
      android:startColor="#FFFFFFFF"
      android:centerColor="#FFFFFF88"
      android:endColor="#FFFFFFFF"
      android:gradientRadius="250"
      android:centerX="1"
      android:centerY="0"
      android:angle="315"
    />            
    </shape>
  </item>
</layer-list>

如果我使用mMyImageView.setBackgroundResource(R.drawable.my_layered_shape)，它就能工作。如果必须的话，我不介意分割XML，或者完全以编程方式完成，只要有一种方法可以访问各种颜色值。在编程中，我追求的概念（即我的最佳代码实现）是：

Drawable[] layers = new Drawable[2];

ShapeDrawable sd1 = new ShapeDrawable(new RectShape());
sd1.getPaint().setColor(0xFFFFFFFF);
sd1.getPaint().setStyle(Style.STROKE);
sd1.getPaint().setStrokeWidth(1);
// sd1.getPaint().somehow_set_stroke_color?

ShapeDrawable sd2 = new ShapeDrawable(new RectShape());
sd2.getPaint().setColor(0xFF000000);
sd2.getPaint().setStyle(Style.STROKE);
// sd2.getPaint().somehow_set_stroke_color?
// sd2.getPaint().somehow_set_gradient_params?

layers[0] = sd1;
layers[1] = sd2;
LayerDrawable composite = new LayerDrawable(layers);
mMyImageView.setBackgroundDrawable(composite);

感谢。

- Carl Whalley

Answer 1

看起来它与 ShapeDrawable 不兼容，但请看我的 GradientDrawable 示例：

GradientDrawable gd = new GradientDrawable(Orientation.BOTTOM_TOP, new int[]{Color.RED, Color.GREEN});
gd.setStroke(10, Color.BLUE);

你可能还需要以下方法：

gd.setGradientCenter(float x, float y);
gd.setGradientRadius(float gradientRadius);

- marnaish

---

奇怪的是，GradientDrawable类没有“setPadding”方法，有什么解决方法吗？ - Palani

Answer 2

我只是把这个放在这里...还没有测试过

 /**
 * Created by Nedo on 09.04.2015.
 */
public class ShapeBuilder {

    public static Drawable generateSelectorFromDrawables(Drawable pressed, Drawable normal) {
        StateListDrawable states = new StateListDrawable();
        states.addState(new int[]{ -android.R.attr.state_focused, -android.R.attr.state_pressed, -android.R.attr.state_selected}, normal);
        states.addState(new int[]{ android.R.attr.state_pressed}, pressed);
        states.addState(new int[]{ android.R.attr.state_focused}, pressed);
        states.addState(new int[]{ android.R.attr.state_selected}, pressed);

        return states;
    }

    public static Drawable generateShape(String colorTop, String colorBot, String colorStroke, int stokeSize, float strokeRadius) {
        int top, bot, stroke;
        top = Color.parseColor(colorTop);
        bot = Color.parseColor(colorBot);
        stroke = Color.parseColor(colorStroke);

        GradientDrawable drawable = new GradientDrawable(GradientDrawable.Orientation.BOTTOM_TOP, new int[]{top, bot});
        drawable.setStroke(stokeSize, stroke);
        drawable.setCornerRadius(strokeRadius);

        return drawable;
    }

    public static Drawable buildSelectorShapeFromColors(String colorNormalStroke, String colorNormalBackTop, String colorNormalBackBot,
                                                        String colorPressedStroke, String colorPressedBackTop, String colorPressedBackBot,
                                                        int strokeSize, float strokeRadius) {

        Drawable pressed = generateShape(colorPressedBackTop, colorPressedBackBot, colorPressedStroke, strokeSize, strokeRadius);
        Drawable normal = generateShape(colorNormalBackTop, colorNormalBackBot, colorNormalStroke, strokeSize, strokeRadius);
        return generateSelectorFromDrawables(pressed, normal);
    }
}

编辑：现在已经测试过，发现一个错误。实际上你需要描述每个单独的状态。如果你将状态分组，只有当它们同时发生时才会触发。

- BooNonMooN