自定义CheckBox样式

drawable目录下新建selector_checkbox.xml文件，指定自定义的样式

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
  <item android:drawable="@drawable/check_selected_blue" android:state_checked="true"/>
  <item android:drawable="@drawable/check_unselected" android:state_checked="false"/>
  <item android:drawable="@drawable/check_unselected"/>
</selector>

在values/styles.xml中定义CustomCheckBox样式，由于自定义样式一般是使用图片素材，如果使用android:button则会发生图片尺寸无法自适应的问题，导致在不同机型上显示效果不一，主要是因为mBackgroundDrawable和mButtonDrawable的尺寸计算不一样，mBackgroundDrawable采用的是view的宽高进行绘制，而mBackgroundDrawable使用的是本身的固有宽高，即图片的固有宽高进行绘制，所以不会随着view的尺寸而自适应。

mButtonDrawable绘制：
    @Override
    protected void onDraw(Canvas canvas) {
        final Drawable buttonDrawable = mButtonDrawable;
        if (buttonDrawable != null) {
            final int verticalGravity = getGravity() & Gravity.VERTICAL_GRAVITY_MASK;
            final int drawableHeight = buttonDrawable.getIntrinsicHeight();
            final int drawableWidth = buttonDrawable.getIntrinsicWidth();

            final int top;
            switch (verticalGravity) {
                case Gravity.BOTTOM:
                    top = getHeight() - drawableHeight;
                    break;
                case Gravity.CENTER_VERTICAL:
                    top = (getHeight() - drawableHeight) / 2;
                    break;
                default:
                    top = 0;
            }
            final int bottom = top + drawableHeight;
            final int left = isLayoutRtl() ? getWidth() - drawableWidth : 0;
            final int right = isLayoutRtl() ? getWidth() : drawableWidth;

            buttonDrawable.setBounds(left, top, right, bottom);
        }

mBackground绘制：
   private void drawBackground(Canvas canvas) {
        final Drawable background = mBackground;
        if (background == null) {
            return;
        }

        setBackgroundBounds();
        ...
    }
    void setBackgroundBounds() {
        if (mBackgroundSizeChanged && mBackground != null) {
            mBackground.setBounds(0, 0, mRight - mLeft, mBottom - mTop);
            mBackgroundSizeChanged = false;
            rebuildOutline();
        }
    }

因此采用android:background替换android:button，完美解决图片尺寸自适应问题

<style name="CustomCheckBox" parent="@android:style/Widget.CompoundButton.CheckBox">
    <item name="android:button">@null</item>
    <item name="android:background">@drawable/selector_checkbox</item>
</style>

最后在代码中指定style即可

<CheckBox
      style="@style/MangatoonCheckBox"
      android:layout_width="20dp"
      android:layout_height="20dp"/>

image.png