Android - how to define ShapeDrawables programmati

问题:

What I'm trying to achieve is to use a Drawable with a couple of layers inside it, but control some values at runtime such as the startColor for the gradient. Here's what I have in my_layered_shape.xml:

<?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>

And if I use mMyImageView.setBackgroundResource(R.drawable.my_layered_shape) it works. I don't mind splitting the xml if I have to, or doing the whole thing programatically as long as there's a way to get at the various color values. The concept I'm going for programmatically (i.e. my best shot at doing the same in code as this xml) is:

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);

Thanks.

回答1:

It seems that is does not work with ShapeDrawable, but take a look at my GradientDrawable example:

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

You may also need following method:

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

回答2:

Just gonna leave this here... Not tested yet

 /**
 * 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);
    }
}

Edit: tested Now, had one mistake. You actually have to describe every single state. If you group states they will only be triggered if all of them accure at once...