Android中Drawable小结

Drawabe是可绘制到屏幕上图形一种概述，屏幕上绘制的图形内容都会最终已Drawable形式提供，Drawable提供了多种展示形式，如下：

    Bitmap: the simplest Drawable, a PNG or JPEG or,GIF image.　　-->BitmapDrawable
    Nine Patch: an extension to the PNG format allows it to specify information about how to stretch it and place things inside of it.　　-->NinePatchDrawable
    Shape: contains simple drawing commands instead of a raw bitmap, allowing it to resize better in some cases.　　-->ShapeDrawable  xml<shape>
    Layers: a compound drawable, which draws multiple underlying drawables on top of each other.　　-->LayerDrawable   xml<layer-list>
    States: a compound drawable that selects one of a set of drawables based on its state. 　　-->StateListDrawable xml<selector>
    Levels: a compound drawable that selects one of a set of drawables based on its level.　　 -->LevelListDrawable xml<level-list>
    Scale: a compound drawable with a single child drawable, whose overall size is modified based on the current level. 　　-->ScaleDrawable xml<scale>

 XML Bitmap：使用xml方式处理Bitmap,例如小图平铺背景

xml定义

<?xml version="1.0" encoding="utf-8"?>
    <bitmap xmlns:android="http://schemas.android.com/apk/res/android"
        android:src="@drawable/icon"
        android:tileMode="repeat" />

 titleMode为Bitmap重复填充方式，tileMode="clamp"填充边缘色

XML Nine-Patch：

    <?xml version="1.0" encoding="utf-8"?>
    <nine-patch
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:src="@[package:]drawable/drawable_resource"
        android:dither=["true" | "false"] />

 LayerDrawable：管理一组drawable显示处理，例如：叠加图形的展示

xml定义：

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
      <bitmap android:src="@drawable/android_red"
        android:gravity="center" />
    </item>
    <item android:top="10dp" android:left="10dp">
      <bitmap android:src="@drawable/android_green"
        android:gravity="center" />
    </item>
    <item android:top="20dp" android:left="20dp">
      <bitmap android:src="@drawable/android_blue"
        android:gravity="center" />
    </item>
</layer-list>

 

layer-list阴影效果：

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <!--底层阴影-->
    <!--top代表下边的阴影高度，left代表右边的阴影宽度 如果不做这个控制，底层和上层的左上会重合在一起-->
    <item
            android:left="2dp"
            android:top="2dp">

        <shape android:shape="rectangle">
            <!--使用渐变色处理阴影色度 angle 0 左边；90 下边，180，右边，270 上边-->
            <gradient
                    android:angle="270"
                    android:endColor="#0F000000"
                    android:startColor="#0F000000"/>

            <corners
                    android:radius="8dp"/>
        </shape>
    </item>

    <!-- 上层背景部分 上层的右边距离底层的右边3,距离底层底部3dp-->
    <item
            android:bottom="3dp"
            android:right="3dp">

        <shape android:shape="rectangle">

            <corners android:radius="8dp"/>
        </shape>
    </item>
</layer-list>

 可参考：https://blog.csdn.net/android_cmos/article/details/80033784

StateListDrawable:根据View的状态来展示不同状态下的Drawable

xml文件:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true"
          android:drawable="@drawable/button_pressed" /> <!-- pressed -->
    <item android:state_focused="true"
          android:drawable="@drawable/button_focused" /> <!-- focused -->
    <item android:state_hovered="true"
          android:drawable="@drawable/button_focused" /> <!-- hovered -->
    <item android:drawable="@drawable/button_normal" /> <!-- default -->
</selector>

LevelListDrawable:展示几张图形，使用setLevel() or setImageLevel()来展示不同Drawable

xml定义:

<?xml version="1.0" encoding="utf-8"?>
<level-list xmlns:android="http://schemas.android.com/apk/res/android" >
    <item
        android:drawable="@drawable/status_off"
        android:maxLevel="0" />
    <item
        android:drawable="@drawable/status_on"
        android:maxLevel="1" />
</level-list>

 TransitionDrawable:限制两个Drawable,淡入淡出效果过度展示

xml定义:

<?xml version="1.0" encoding="utf-8"?>
<transition xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/on" />
    <item android:drawable="@drawable/off" />
</transition>

 使用:

ImageButton button = (ImageButton) findViewById(R.id.button);
TransitionDrawable drawable = (TransitionDrawable) button.getDrawable();
drawable.startTransition(500);

 InsetDrawable：嵌入到另一个Drawable里，指定边距区域显示，例如：背景区域小于内容区可使用

xml文件:

<?xml version="1.0" encoding="utf-8"?>
    <inset
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:drawable="@drawable/drawable_resource"
        android:insetTop="dimension"
        android:insetRight="dimension"
        android:insetBottom="dimension"
        android:insetLeft="dimension" />

ScaleDrawable:对Drawable的尺寸进行拉伸处理
xml定义:

  <?xml version="1.0" encoding="utf-8"?>
    <scale xmlns:android="http://schemas.android.com/apk/res/android"
        android:drawable="@drawable/logo"
        android:scaleGravity="center_vertical|center_horizontal"
        android:scaleHeight="80%"
        android:scaleWidth="80%" />

ClipDrawable：裁剪处理

<?xml version="1.0" encoding="utf-8"?>
<clip xmlns:android="http://schemas.android.com/apk/res/android"
    android:drawable="@drawable/android"
    android:clipOrientation="horizontal"
    android:gravity="left" />

/** 
	* Drawable转化为Bitmap 
	*/  
	public static Bitmap drawableToBitmap(Drawable drawable) {  
	   int width = drawable.getIntrinsicWidth();  
	   int height = drawable.getIntrinsicHeight();  
	   Bitmap bitmap = Bitmap.createBitmap(width, height, drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565);  
	   Canvas canvas = new Canvas(bitmap);  
	   drawable.setBounds(0, 0, width, height);  
	   drawable.draw(canvas);  
	   return bitmap;  
	  
	}  
	/**
	 * Bitmap to Drawable
	 * @param bitmap
	 * @param mcontext
	 * @return
	 */
	public static Drawable bitmapToDrawble(Bitmap bitmap,Context mcontext){
		Drawable drawable = new BitmapDrawable(mcontext.getResources(), bitmap);
		return drawable;
	}