Android 成长在于积累和分享

本文：https://blog.csdn.net/CrazyApes/article/details/122677466

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前言

Andoid 中很多圆角或者边线的操作都喜欢用 shape 实现。
那么很多需求会用到根据特定的状态去展示当前的颜色，这个时候，可能就需要动态修改 shape 的颜色了。
当然也有小伙伴选择直接重写几个shape代表不同的状态。哈哈。

除此之外，也可以考虑使用material中的相关View实现，这个后话在说。

解决方案

答案要写在前面，分析可以后面慢慢看

修改Solid颜色

// Java 
GradientDrawable shapeDrawable = (GradientDrawable) mShapeView.getBackground();
shapeDrawable.setColor(mShapeView.getResources().getColor(color));

// kotlin
val shapeDrawable = mShapeView.getBackground() as GradientDrawable
shapeDrawable.setColor(mShapeView.resources.getColor(color))

修改Stroke颜色

// Java 
GradientDrawable shapeDrawable  = (GradientDrawable) mShapeView.getBackground();
shapeDrawable.setStroke((int)Utils.dpToPx(mContext,1),mShapeView.getResources().getColor(color));

// kotlin
val shapeDrawable = mShapeView.getBackground() as GradientDrawable
shapeDrawable.setStroke(1.dp,mShapeView.resources.getColor(color))

Shape

假设我现在有一个正在使用的 shape 了，
一个底部左右圆角，带白色边框红色内部的样式
如下：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">

    <corners
        android:bottomLeftRadius="6dp"
        android:bottomRightRadius="6dp"/>

    <stroke android:width="1dp"
        android:color="@color/white" />

    <solid android:color="@color/red"/>

</shape>

大致效果如图：

shape.png

shape对应的GradientDrawable

首先，我们先确认shape对应的Drawable是哪个，这个可以通过Debug查看。

可以通过layout的xml设置给 background
或者在代码中直接通过 getResource().getDrawable(resId)

debug结果如图：

image.png

结果显示：
shape对应的Drawable为 GradientDrawable

GradientDrawable

然后我们再看GradientDrawable的源码。
在注释说明中确认了，shape最终对应的就是GradientDrawable
并且在xml中定义的属性，都可以看得到。

条件允许的话，可以通篇看一遍源码。
这里只摘录了一部分。

package android.graphics.drawable;

import ...

/**
 * A Drawable with a color gradient for buttons, backgrounds, etc.
 *
 * <p>It can be defined in an XML file with the <code>&lt;shape></code> element. For more
 * information, see the guide to <a
 * href="{@docRoot}guide/topics/resources/drawable-resource.html">Drawable Resources</a>.</p>
 *
 * @attr ref android.R.styleable#GradientDrawable_visible
 * @attr ref android.R.styleable#GradientDrawable_shape
 * @attr ref android.R.styleable#GradientDrawable_innerRadiusRatio
 * @attr ref android.R.styleable#GradientDrawable_innerRadius
 * @attr ref android.R.styleable#GradientDrawable_thicknessRatio
 * @attr ref android.R.styleable#GradientDrawable_thickness
 * @attr ref android.R.styleable#GradientDrawable_useLevel
 * @attr ref android.R.styleable#GradientDrawableSize_width
 * @attr ref android.R.styleable#GradientDrawableSize_height
 * @attr ref android.R.styleable#GradientDrawableGradient_startColor
 * @attr ref android.R.styleable#GradientDrawableGradient_centerColor
 * @attr ref android.R.styleable#GradientDrawableGradient_endColor
 * @attr ref android.R.styleable#GradientDrawableGradient_useLevel
 * @attr ref android.R.styleable#GradientDrawableGradient_angle
 * @attr ref android.R.styleable#GradientDrawableGradient_type
 * @attr ref android.R.styleable#GradientDrawableGradient_centerX
 * @attr ref android.R.styleable#GradientDrawableGradient_centerY
 * @attr ref android.R.styleable#GradientDrawableGradient_gradientRadius
 * @attr ref android.R.styleable#GradientDrawableSolid_color
 * @attr ref android.R.styleable#GradientDrawableStroke_width
 * @attr ref android.R.styleable#GradientDrawableStroke_color
 * @attr ref android.R.styleable#GradientDrawableStroke_dashWidth
 * @attr ref android.R.styleable#GradientDrawableStroke_dashGap
 * @attr ref android.R.styleable#GradientDrawablePadding_left
 * @attr ref android.R.styleable#GradientDrawablePadding_top
 * @attr ref android.R.styleable#GradientDrawablePadding_right
 * @attr ref android.R.styleable#GradientDrawablePadding_bottom
 */
public class GradientDrawable extends Drawable {
        ....
}

修改solid颜色

在源码中找到和solid颜色相关的代码

• 1.XML中属性解析
  <solid android:color="@color/red"/>
  结合源码开头的注释，可以看到对应的的styleable属性为：GradientDrawableSolid_color
• 2.整个文件检索相关方法
  检索 GradientDrawableSolid_color
  发现在 updateGradientDrawableSolid 方法中解析并使用
  并且最终调用了 setColor 方法
• 3.查看setColor相关源码
  有两处相关，
  分别是：setColor(@ColorInt int argb)
  和：setColor(@Nullable ColorStateList colorStateList)
  从源码可见，二者实现逻辑基本一致（详见下方源码）
  并且从方法注释解读确认确实是需要找的填充色。
• 4.确认最终实现方式
  修改Solid颜色调用setColor方法即可。
  参数可选ColorInt 或者 ColorStateList均可。

package android.graphics.drawable;

import ...

/**
 * ...
 * @attr ref android.R.styleable#GradientDrawableSolid_color
 * ...
 */
public class GradientDrawable extends Drawable {
    ....
    private void updateGradientDrawableSolid(TypedArray a) {
        final GradientState st = mGradientState;

        // Account for any configuration changes.
        st.mChangingConfigurations |= a.getChangingConfigurations();

        // Extract the theme attributes, if any.
        st.mAttrSolid = a.extractThemeAttrs();

        // 从xml中获取Soild Color颜色
        final ColorStateList colorStateList = a.getColorStateList(
                R.styleable.GradientDrawableSolid_color);
        if (colorStateList != null) {
            setColor(colorStateList);
        }
    }
    ....
    /**
     * Changes this drawable to use a single color instead of a gradient.
     * <p>
     * <strong>Note</strong>: changing color will affect all instances of a
     * drawable loaded from a resource. It is recommended to invoke
     * {@link #mutate()} before changing the color.
     *
     * @param argb The color used to fill the shape
     *
     * @see #mutate()
     * @see #setColors(int[])
     * @see #getColor
     */
    public void setColor(@ColorInt int argb) {
        mGradientState.setSolidColors(ColorStateList.valueOf(argb));
        mFillPaint.setColor(argb);
        invalidateSelf();
    }

    /**
     * Changes this drawable to use a single color state list instead of a
     * gradient. Calling this method with a null argument will clear the color
     * and is equivalent to calling {@link #setColor(int)} with the argument
     * {@link Color#TRANSPARENT}.
     * <p>
     * <strong>Note</strong>: changing color will affect all instances of a
     * drawable loaded from a resource. It is recommended to invoke
     * {@link #mutate()} before changing the color.</p>
     *
     * @param colorStateList The color state list used to fill the shape
     *
     * @see #mutate()
     * @see #getColor
     */
    public void setColor(@Nullable ColorStateList colorStateList) {
        mGradientState.setSolidColors(colorStateList);
        final int color;
        if (colorStateList == null) {
            color = Color.TRANSPARENT;
        } else {
            final int[] stateSet = getState();
            color = colorStateList.getColorForState(stateSet, 0);
        }
        mFillPaint.setColor(color);
        invalidateSelf();
    }

    /**
     * Returns the color state list used to fill the shape, or {@code null} if
     * the shape is filled with a gradient or has no fill color.
     *
     * @return the color state list used to fill this gradient, or {@code null}
     *
     * @see #setColor(int)
     * @see #setColor(ColorStateList)
     */
    @Nullable
    public ColorStateList getColor() {
        return mGradientState.mSolidColors;
    }
}

修改Stroke颜色

跟Solid一样的方式，在源码中找到和Stroke颜色相关的代码

• 1. XML中的属性解析
     <stroke android:color="@color/black"/>
     结合源码开头的注释，可以看到对应的的styleable属性为：GradientDrawableStroke_color
• 2.整个文件检索相关方法
  检索 GradientDrawableStroke_color
  发现在 updateGradientDrawableStroke 方法中解析并使用
  并且最终调用了 setStroke 方法
• 3.查看setStroke相关源码
  有四处多态相关，
  分别是：
  setStroke(int width, @ColorInt int color)
setStroke(int width, ColorStateList colorStateList)
setStroke(int width, @ColorInt int color, float dashWidth, float dashGap)
setStroke(int width, ColorStateList colorStateList, float dashWidth, float dashGap)
  这个和Solid的颜色方式一样，
  从源码可见，实现逻辑基本一致（详见下方源码）
  并且从方法注释解读确认确实是需要找的填充色。
• 4.确认最终实现方式
  修改Stroke颜色调用setStroke方法即可。

package android.graphics.drawable;

import ...

/**
 * ...
 * @attr ref android.R.styleable#GradientDrawableStroke_color
 * ...
 */
public class GradientDrawable extends Drawable {
    ....
    private void updateGradientDrawableStroke(TypedArray a) {
        final GradientState st = mGradientState;

        // Account for any configuration changes.
        st.mChangingConfigurations |= a.getChangingConfigurations();

        // Extract the theme attributes, if any.
        st.mAttrStroke = a.extractThemeAttrs();

        // We have an explicit stroke defined, so the default stroke width
        // must be at least 0 or the current stroke width.
        final int defaultStrokeWidth = Math.max(0, st.mStrokeWidth);
        final int width = a.getDimensionPixelSize(
                R.styleable.GradientDrawableStroke_width, defaultStrokeWidth);
        final float dashWidth = a.getDimension(
                R.styleable.GradientDrawableStroke_dashWidth, st.mStrokeDashWidth);

        ColorStateList colorStateList = a.getColorStateList(
                R.styleable.GradientDrawableStroke_color);
        if (colorStateList == null) {
            colorStateList = st.mStrokeColors;
        }

        if (dashWidth != 0.0f) {
            final float dashGap = a.getDimension(
                    R.styleable.GradientDrawableStroke_dashGap, st.mStrokeDashGap);
            setStroke(width, colorStateList, dashWidth, dashGap);
        } else {
            setStroke(width, colorStateList);
        }
    }
    ....
    /**
     * <p>Set the stroke width and color for the drawable. If width is zero,
     * then no stroke is drawn.</p>
     * <p><strong>Note</strong>: changing this property will affect all instances
     * of a drawable loaded from a resource. It is recommended to invoke
     * {@link #mutate()} before changing this property.</p>
     *
     * @param width The width in pixels of the stroke
     * @param color The color of the stroke
     *
     * @see #mutate()
     * @see #setStroke(int, int, float, float)
     */
    public void setStroke(int width, @ColorInt int color) {
        setStroke(width, color, 0, 0);
    }

    /**
     * <p>Set the stroke width and color state list for the drawable. If width
     * is zero, then no stroke is drawn.</p>
     * <p><strong>Note</strong>: changing this property will affect all instances
     * of a drawable loaded from a resource. It is recommended to invoke
     * {@link #mutate()} before changing this property.</p>
     *
     * @param width The width in pixels of the stroke
     * @param colorStateList The color state list of the stroke
     *
     * @see #mutate()
     * @see #setStroke(int, ColorStateList, float, float)
     */
    public void setStroke(int width, ColorStateList colorStateList) {
        setStroke(width, colorStateList, 0, 0);
    }

    /**
     * <p>Set the stroke width and color for the drawable. If width is zero,
     * then no stroke is drawn. This method can also be used to dash the stroke.</p>
     * <p><strong>Note</strong>: changing this property will affect all instances
     * of a drawable loaded from a resource. It is recommended to invoke
     * {@link #mutate()} before changing this property.</p>
     *
     * @param width The width in pixels of the stroke
     * @param color The color of the stroke
     * @param dashWidth The length in pixels of the dashes, set to 0 to disable dashes
     * @param dashGap The gap in pixels between dashes
     *
     * @see #mutate()
     * @see #setStroke(int, int)
     */
    public void setStroke(int width, @ColorInt int color, float dashWidth, float dashGap) {
        mGradientState.setStroke(width, ColorStateList.valueOf(color), dashWidth, dashGap);
        setStrokeInternal(width, color, dashWidth, dashGap);
    }

    /**
     * <p>Set the stroke width and color state list for the drawable. If width
     * is zero, then no stroke is drawn. This method can also be used to dash
     * the stroke.</p>
     * <p><strong>Note</strong>: changing this property will affect all instances
     * of a drawable loaded from a resource. It is recommended to invoke
     * {@link #mutate()} before changing this property.</p>
     *
     * @param width The width in pixels of the stroke
     * @param colorStateList The color state list of the stroke
     * @param dashWidth The length in pixels of the dashes, set to 0 to disable dashes
     * @param dashGap The gap in pixels between dashes
     *
     * @see #mutate()
     * @see #setStroke(int, ColorStateList)
     */
    public void setStroke(
            int width, ColorStateList colorStateList, float dashWidth, float dashGap) {
        mGradientState.setStroke(width, colorStateList, dashWidth, dashGap);
        final int color;
        if (colorStateList == null) {
            color = Color.TRANSPARENT;
        } else {
            final int[] stateSet = getState();
            color = colorStateList.getColorForState(stateSet, 0);
        }
        setStrokeInternal(width, color, dashWidth, dashGap);
    }

}

结语

还有其它的相关属性都可以根据源码中的实现和开放的api进行操作。
不再一一列举，熟读源码即可。
或者参考文章尾部的官方Api文档。

参考文献

https://developer.android.google.cn/reference/android/graphics/drawable/GradientDrawable