Drawable

概述

• Drawable是一个抽象类,是对可绘制物体的抽象.与View不同的是Drawable没有事件和交互方法
• Drawable 有好多子类操作具体类型资源,比如
  • BitmapDrawable是用来操作位图
  • ColorDrawable用来操作颜色
  • ClipDrawable用来操作剪切板

原理

• draw(Canvas canvas)
• setBounds()

BitmapDrawable

是对bitmap的一种包装，可一设置它包装的bitmap在BitmapDrawable区域内的绘制方式 如平铺填充，拉伸填充或者保持图片原始大小

<?xml version="1.0" encoding="utf-8"?>
<bitmap  xmlns:android="http://schemas.android.com/apk/res/android"
    android:src="@drawable/ic_pause"  //不支持XML图片
    android:tileMode="mirror"
    android:antialias="true"
    android:dither="true">
</bitmap >

LayerDrawable

可以管理一组drawable对象在LayerDrawable的drawable资源按照列表的顺序绘制,列表的最后一个drawable绘制在上层

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

    <item
        android:gravity="center"
        android:left="50dp">
        <bitmap android:src="@drawable/ic_pause" />
    </item>
</layer-list>

StatusListDrawable

就是selector

LevelListDrawable

<?xml version="1.0" encoding="utf-8"?>
<level-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:drawable="@drawable/ic_pause"
        android:maxLevel="10"
        android:minLevel="6" />

    <item
        android:drawable="@drawable/ic_start"
        android:maxLevel="20"
        android:minLevel="11" />
</level-list>

iv_name.setImageLevel(8); //根据设置不同的level显示不同的图片

TransitionDrawable

它只负责管理两层drawable,并且提供了一个透明度变化的动画,可以控制从一层drawable过度到另一层drawable的动画效果。
适合lian两幅同样的图片但是颜色不一样 显示过度效果

<?xml version="1.0" encoding="utf-8"?>
<transition xmlns:android="http://schemas.android.com/apk/res/android">
    <item  //始终显示的图片
        android:drawable="@drawable/ic_start" />
    <item //渐变显示的图片
        android:drawable="@drawable/ic_pause" />
</transition>

 TransitionDrawable drawable = (TransitionDrawable) iv_name.getDrawable();
                drawable.reverseTransition(1000);

InsertDrawable

效果和 pading差不多

<?xml version="1.0" encoding="utf-8"?>
<inset xmlns:android="http://schemas.android.com/apk/res/android"
    android:drawable="@drawable/ic_launcher_background"
    android:insetLeft="25dp" //效果和 pading差不多 
    android:insetBottom="25dp"
    android:insetRight="25dp"
    android:insetTop="25dp">
</inset>

ClipDrawable

• ClicpDrawable是对Drawable尽享剪切操作,控制剪切区域
• android中的进度条就是使用ClipDrawable实现效果的,它根据level的属性值,决定剪切区域的大小
• ClipDrawable通过setLevel() 方法来设置剪切区域,level从0到1000,当为0时完全不显示,为10000时完全显示

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

 ClipDrawable background = (ClipDrawable) iv_name.getDrawable();
        background.setLevel(6000);

自定义Drawable

public class CircleDrawable extends Drawable {
    private Paint mPaint;
    private int mWidth;
    private Bitmap mBitmap;
    private final BitmapShader bitmapShader;

    public CircleDrawable(Bitmap mBitmap) {
        this.mBitmap = mBitmap;
        //着色器
        bitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setShader(bitmapShader);
        mWidth = Math.min(mBitmap.getHeight(), mBitmap.getWidth());
    }
    @Override
    public void draw(@NonNull Canvas canvas) {
        canvas.drawCircle(mWidth/2,mWidth/2,mWidth/2,mPaint);
    }
    @Override
    public void setAlpha(int i) {
            mPaint.setAlpha(i);//设置画笔的透明度
    }
    @Override //设置画笔的ColorFilter
    public void setColorFilter(@Nullable ColorFilter colorFilter) {
          mPaint.setColorFilter(colorFilter);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }
    @Override
    public int getIntrinsicWidth() {
        return mWidth;
    }
    @Override
    public int getIntrinsicHeight() {
        return mWidth;
    }
}


  ImageView iv_name = findViewById(R.id.iv_name);
        CircleDrawable circleDrawable = new CircleDrawable(BitmapFactory.decodeResource(getResources(),R.drawable.th));
        iv_name.setImageDrawable(circleDrawable);

    public class Rect1Drawable extends Drawable {
    private Paint mPaint;
    private Bitmap mBitmap;
    private RectF rect;
    private final BitmapShader bitmapShader;

    public Rect1Drawable(Bitmap mBitmap) {
        this.mBitmap = mBitmap;
        //着色器
        bitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setShader(bitmapShader);

    }
    @Override
    public void draw(@NonNull Canvas canvas) {
        canvas.drawRoundRect(rect,60,60,mPaint);
    }


    @Override
    public void setBounds(int left, int top, int right, int bottom) {
        rect=new RectF(left, top, right, bottom);
    }

    @Override
    public void setAlpha(int i) {
            mPaint.setAlpha(i);//设置画笔的透明度
    }
    @Override //设置画笔的ColorFilter
    public void setColorFilter(@Nullable ColorFilter colorFilter) {
          mPaint.setColorFilter(colorFilter);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }
    @Override
    public int getIntrinsicWidth() {
        return mBitmap.getWidth();
    }
    @Override
    public int getIntrinsicHeight() {
        return mBitmap.getHeight();
    }
}