Android 开发之 Drawable系列
Android开发中遇到不少地方须要drawable资源，而drawable的种类繁多，好比shape绘制纯色图片，.9.png图片适应拉伸。当咱们充分了解drawable的子类后，就会发现，原来能够如此简单。java
- BitmapDrawable
- NinePathDrawable
- LayerDrawable
- StateListDrawable
- LevelDrawable
- TransitionDrawable
- Inset Drawable
- ClipDrawable
- ScaleDrawable
- ShapeDrawable ….
android:antialias:抗锯齿，canvas 绘图对位图进行了选择，会出现锯齿，一般解决办法是经过Paint mPaint=new Paint();调用 mPaint.setAntiAlias()方法。android:filter用于对位图进行过滤波处理。android:dither:图像的抖动处理，当每一个颜色值以低于8位表示时，对应图像作抖动处理能够实如今可显示颜色总数比较低时还保持较好的显示效果.android:mipMap hasMipMap()这里的提一下drawable和mipMap的区别，android studio开发工具里面：原生图片放在mipmap 里面， drawable主要放一些放一些自定义形状和按钮变色之类的xml。google强烈建议使用mipmap装图片。把图片放到mipmaps能够提升系统渲染图片的速度，提升图片质量，减小GPU压力。android:tileMode平铺，xml实例以下：android
<bitmap xmlns:android="http://schemas.android.com/apk/res/android" android:src="@drawable/test" android:tileMode="repeat" android:dither="true" />
代码调用以下：web
Bitmap mBitmap = BitmapFactory.decodeResource(mContext.getResources(), R.drawable.ic_launcher);
BitmapDrawable mBitmapDrawable = new BitmapDrawable(mBitmap);
mBitmapDrawable.setTileModeXY(TileMode.REPEAT , TileMode.REPEAT );
mBitmapDrawable.setDither(true);
mLayout.setBackgroundDrawable(mBitmapDrawable);
这里的TileMode类源自Shader类里面的枚举类型，源代码以下：canvas
public enum TileMode {
/** * replicate the edge color if the shader draws outside of its * original bounds */
CLAMP (0),
/** * repeat the shader's image horizontally and vertically */
REPEAT (1),
/** * repeat the shader's image horizontally and vertically, alternating * mirror images so that adjacent images always seam */
MIRROR (2);
TileMode(int nativeInt) {
this.nativeInt = nativeInt;
}
final int nativeInt;
}
BitmapDrawable构造函数数组
android.graphics.drawable
public class BitmapDrawable extends Drawable{
// public static final int DENSITY_DEFAULT = DENSITY_MEDIUM=160;
private int mTargetDensity = DisplayMetrics.DENSITY_DEFAULT;
public BitmapDrawable() {
mBitmapState = new BitmapState((Bitmap) null);
}
public BitmapDrawable(Resources res) {
mBitmapState = new BitmapState((Bitmap) null);
mBitmapState.mTargetDensity = mTargetDensity;
}
public BitmapDrawable(Bitmap bitmap) {
this(new BitmapState(bitmap), null);
}
public BitmapDrawable(Resources res, Bitmap bitmap) {
this(new BitmapState(bitmap), res);
mBitmapState.mTargetDensity = mTargetDensity;
}
public BitmapDrawable(String filepath) {
this(new BitmapState(BitmapFactory.decodeFile(filepath)), null);
if (mBitmapState.mBitmap == null) {
android.util.Log.w("BitmapDrawable", "BitmapDrawable cannot decode " + filepath);
}
}
public BitmapDrawable(Resources res, String filepath) {
this(new BitmapState(BitmapFactory.decodeFile(filepath)), null);
mBitmapState.mTargetDensity = mTargetDensity;
if (mBitmapState.mBitmap == null) {
android.util.Log.w("BitmapDrawable", "BitmapDrawable cannot decode " + filepath);
}
}
public BitmapDrawable(java.io.InputStream is) {
this(new BitmapState(BitmapFactory.decodeStream(is)), null);
if (mBitmapState.mBitmap == null) {
android.util.Log.w("BitmapDrawable", "BitmapDrawable cannot decode " + is);
}
}
public BitmapDrawable(Resources res, java.io.InputStream is) {
this(new BitmapState(BitmapFactory.decodeStream(is)), null);
mBitmapState.mTargetDensity = mTargetDensity;
if (mBitmapState.mBitmap == null) {
android.util.Log.w("BitmapDrawable", "BitmapDrawable cannot decode " + is);
}
}
/** * The one constructor to rule them all. This is called by all public * constructors to set the state and initialize local properties. */
private BitmapDrawable(BitmapState state, Resources res) {
mBitmapState = state;
initializeWithState(mBitmapState, res);
}
}
这里都调用了一个BitmapState的类，而BitmapState extends Drawable.ConstantState。重写其抽象方法app
public static abstract class ConstantState {
/** * Create a new drawable without supplying resources the caller * is running in. Note that using this means the density-dependent * drawables (like bitmaps) will not be able to update their target * density correctly. One should use {@link #newDrawable(Resources)} * instead to provide a resource. */
public abstract Drawable newDrawable();
/** * Create a new Drawable instance from its constant state. This * must be implemented for drawables that change based on the target * density of their caller (that is depending on whether it is * in compatibility mode). */
public Drawable newDrawable(Resources res) {
return newDrawable();
}
/** * Create a new Drawable instance from its constant state. This must be * implemented for drawables that can have a theme applied. */
public Drawable newDrawable(Resources res, Theme theme) {
return newDrawable(null);
}
/** * Return a bit mask of configuration changes that will impact * this drawable (and thus require completely reloading it). */
public abstract int getChangingConfigurations();
/** * @return Total pixel count * @hide */
public int addAtlasableBitmaps(Collection<Bitmap> atlasList) {
return 0;
}
/** @hide */
protected final boolean isAtlasable(Bitmap bitmap) {
return bitmap != null && bitmap.getConfig() == Bitmap.Config.ARGB_8888;
}
/** * Return whether this constant state can have a theme applied. */
public boolean canApplyTheme() {
return false;
}
}
获得BitmapDrawable instance后，可动态设置attr, BitmapDrawable的在new的时候，重写Drawable的私有空方法,重写测量后设置Paint的shaderide
/** * Override this in your subclass to change appearance if you vary based on * the bounds. */
protected void onBoundsChange(Rect bounds) {}
@Override
protected void onBoundsChange(Rect bounds) {
mDstRectAndInsetsDirty = true;
final Shader shader = mBitmapState.mPaint.getShader();
if (shader != null) {
if (needMirroring()) {
updateMirrorMatrix(bounds.right - bounds.left);
shader.setLocalMatrix(mMirrorMatrix);
mBitmapState.mPaint.setShader(shader);
} else {
if (mMirrorMatrix != null) {
mMirrorMatrix = null;
shader.setLocalMatrix(Matrix.IDENTITY_MATRIX);
mBitmapState.mPaint.setShader(shader);
}
}
}
}
getIntrinsicHeight()和getIntrinsicWidth()方法获取BitmapDrawable的宽高，即按照比例缩放后实际大小值。同时须要注意BitmapDrawable(Bitmap mBitmap)已经被弃用,若是延用该方法可能会出现问题mTargetDensity默认的是160，当mBitmap的density>160的时候,bitmap.getWidth() != bitmapDrawable.getIntrinsicWidth().解决办法是传入Resources或者调用setTargetDensity()方法，这样就没问题了。public 构造方法都调用自身的private构造方法，该方法内调用initializeWithState(mBitmapState, res)对mTargetDensity从新赋值，方法以下：svg
/** * Initializes local dynamic properties from state. This should be called * after significant state changes, e.g. from the One True Constructor and * after inflating or applying a theme. */
private void initializeWithState(BitmapState state, Resources res) {
if (res != null) {
mTargetDensity = res.getDisplayMetrics().densityDpi;
} else {
mTargetDensity = state.mTargetDensity;
}
mTintFilter = updateTintFilter(mTintFilter, state.mTint, state.mTintMode);
computeBitmapSize();
}
下面是一个代码调用实例函数
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
image=(ImageView)findViewById(R.id.image);
image.setBackground(getBitmapDrawable());
}
private Drawable getBitmapDrawable() {
BitmapDrawable mBitmapDrawable=new BitmapDrawable(getResources(),BitmapFactory.decodeResource(getResources(), R.drawable.anglebaby));
mBitmapDrawable.setAlpha(1000);
mBitmapDrawable.setAntiAlias(true);
mBitmapDrawable.setDither(true);
mBitmapDrawable.setFilterBitmap(true);
mBitmapDrawable.setTileModeXY(TileMode.REPEAT,TileMode.REPEAT);
mBitmapDrawable.setColorFilter(Color.parseColor("#40FF0000"), Mode.SRC_ATOP);
return mBitmapDrawable;
}
NinePatchDrawable该类与BitmapDrawable大同小异，NinePatchDrawable构造方法要传入NinePath和byte[],对指定区域进行屏幕的左右上下拉伸，也能够直接用sdk自带的工具制做.9图片。下面是代码调用实例：工具
private Drawable getNinePatchDrawable() {
Bitmap mBitmap=BitmapFactory.decodeResource(getResources(), R.drawable.anglebabye);
NinePatchDrawable mNinePatchDrawable=new NinePatchDrawable(getResources(), new NinePatch(mBitmap, mBitmap.getNinePatchChunk()));
mNinePatchDrawable.setAlpha(1000);
mNinePatchDrawable.setDither(true);
mNinePatchDrawable.setFilterBitmap(true);
mNinePatchDrawable.setTintMode(Mode.SRC_ATOP);//API 21
mNinePatchDrawable.setColorFilter(Color.parseColor("#40FF0000"), Mode.SRC_ATOP);
return mNinePatchDrawable;
}
/** * Private constructor that must received an already allocated native bitmap * int (pointer). */
@SuppressWarnings({"UnusedDeclaration"}) // called from JNI
Bitmap(long nativeBitmap, byte[] buffer, int width, int height, int density,
boolean isMutable, boolean requestPremultiplied,
byte[] ninePatchChunk, NinePatch.InsetStruct ninePatchInsets) {
if (nativeBitmap == 0) {
throw new RuntimeException("internal error: native bitmap is 0");
}
mWidth = width;
mHeight = height;
mIsMutable = isMutable;
mRequestPremultiplied = requestPremultiplied;
mBuffer = buffer;
// we delete this in our finalizer
mNativeBitmap = nativeBitmap;
mNinePatchChunk = ninePatchChunk;
mNinePatchInsets = ninePatchInsets;
if (density >= 0) {
mDensity = density;
}
int nativeAllocationByteCount = buffer == null ? getByteCount() : 0;
mFinalizer = new BitmapFinalizer(nativeBitmap, nativeAllocationByteCount);
}
...mBitmap.getNinePatchChunk()>mNinePatchChunk对应这块的传值暂不涉及...
官方xml实例以下：
<?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>
<ImageView android:layout_height="wrap_content" android:layout_width="wrap_content" android:src="@drawable/layers" />
LayerDrawable类继承Drawable 实现Drawable的Callback方法invalidateDrawable、 scheduleDrawable、unscheduleDrawable;先了解LayerDrawable的构造方法：
public LayerDrawable(Drawable[] layers) {
this(layers, null);
}
LayerDrawable(Drawable[] layers, LayerState state) {
this(state, null);
final int length = layers.length;
final ChildDrawable[] r = new ChildDrawable[length];
for (int i = 0; i < length; i++) {
r[i] = new ChildDrawable();
r[i].mDrawable = layers[i];
layers[i].setCallback(this);
mLayerState.mChildrenChangingConfigurations |= layers[i].getChangingConfigurations();
}
mLayerState.mNum = length;
mLayerState.mChildren = r;
ensurePadding();
}
LayerDrawable() {
this((LayerState) null, null);
}
LayerDrawable(LayerState state, Resources res) {
mLayerState = createConstantState(state, res);
if (mLayerState.mNum > 0) {
ensurePadding();
}
}
LayerState的Configuration从新赋值后，调用ensurePadding计算四个方向的padding值。inflate方法里面经过TypeArray获取自定义属性从新赋值
/** * Initializes the constant state from the values in the typed array. */
private void updateStateFromTypedArray(TypedArray a) {
final LayerState state = mLayerState;
// Account for any configuration changes.
state.mChangingConfigurations |= a.getChangingConfigurations();
// Extract the theme attributes, if any.
state.mThemeAttrs = a.extractThemeAttrs();
mOpacityOverride = a.getInt(R.styleable.LayerDrawable_opacity, mOpacityOverride);
state.mAutoMirrored = a.getBoolean(R.styleable.LayerDrawable_autoMirrored,
state.mAutoMirrored);
state.mPaddingMode = a.getInteger(R.styleable.LayerDrawable_paddingMode,
state.mPaddingMode);
}
再调用inflateLayers方法，XmlPullParser解析后调用 updateLayerFromTypedArray(layer, a),获取xml的属性值，方法以下：
private void updateLayerFromTypedArray(ChildDrawable layer, TypedArray a) {
final LayerState state = mLayerState;
// Account for any configuration changes.
state.mChildrenChangingConfigurations |= a.getChangingConfigurations();
// Extract the theme attributes, if any.
layer.mThemeAttrs = a.extractThemeAttrs();
layer.mInsetL = a.getDimensionPixelOffset(
R.styleable.LayerDrawableItem_left, layer.mInsetL);
layer.mInsetT = a.getDimensionPixelOffset(
R.styleable.LayerDrawableItem_top, layer.mInsetT);
layer.mInsetR = a.getDimensionPixelOffset(
R.styleable.LayerDrawableItem_right, layer.mInsetR);
layer.mInsetB = a.getDimensionPixelOffset(
R.styleable.LayerDrawableItem_bottom, layer.mInsetB);
layer.mId = a.getResourceId(R.styleable.LayerDrawableItem_id, layer.mId);
final Drawable dr = a.getDrawable(R.styleable.LayerDrawableItem_drawable);
if (dr != null) {
layer.mDrawable = dr;
}
}
Drawable的padding值判断是否须要刷新，若是Padding值发生变化，就return true
/** * Refreshes the cached padding values for the specified child. * * @return true if the child's padding has changed */
private boolean refreshChildPadding(int i, ChildDrawable r) {
final Rect rect = mTmpRect;
r.mDrawable.getPadding(rect);
if (rect.left != mPaddingL[i] || rect.top != mPaddingT[i] ||
rect.right != mPaddingR[i] || rect.bottom != mPaddingB[i]) {
mPaddingL[i] = rect.left;
mPaddingT[i] = rect.top;
mPaddingR[i] = rect.right;
mPaddingB[i] = rect.bottom;
return true;
}
return false;
}
onDraw方法把图片集合绘制到画布，其余方法都大同小异，暂不贴了。
@Override
public void draw(Canvas canvas) {
final ChildDrawable[] array = mLayerState.mChildren;
final int N = mLayerState.mNum;
for (int i = 0; i < N; i++) {
array[i].mDrawable.draw(canvas);
}
}
代码调用LayerDrawable实例直接new 传入Drawable数组便可。不过须要注意：getResource.getDrawable(int id)一过期， 废弃方法：getDrawable(int id)替代方法：getDrawable(int id, Resources.Theme theme), 废弃缘由：在JELLY_BEAN（Android 4.1版本）之前,id是另外一个Drawable资源的别名, 则该方法不能正确地获取到正确配置density。density与实际资源的density不等，缩放会出问题。StateListDrawable与LayerDrawable相差不大，StatListDrawable的对应xml实例以下：
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"
android:constantSize=["true" | "false"]
android:dither=["true" | "false"]
android:variablePadding=["true" | "false"] >
<item
android:drawable="@[package:]drawable/drawable_resource"
android:state_pressed=["true" | "false"]
android:state_focused=["true" | "false"]
android:state_hovered=["true" | "false"]
android:state_selected=["true" | "false"]
android:state_checkable=["true" | "false"]
android:state_checked=["true" | "false"]
android:state_enabled=["true" | "false"]
android:state_activated=["true" | "false"]
android:state_window_focused=["true" | "false"] />
</selector>
咱们一块儿经常使用的selector控制点击效果，说白了就是一个StateListDrawable,代码调用能够直接使用StateListDrawable提供的方法：
/** * Add a new image/string ID to the set of images. * * @param stateSet - An array of resource Ids to associate with the image. * Switch to this image by calling setState(). * @param drawable -The image to show. */
public void addState(int[] stateSet, Drawable drawable) {
if (drawable != null) {
mStateListState.addStateSet(stateSet, drawable);
// in case the new state matches our current state...
onStateChange(getState());
}
}
代码调用实例以下：
StateListDrawable mStateListDrawable=new StateListDrawable();
mStateListDrawable.addState(new int[]{android.R.attr.state_focused}, getDrawable(R.drawable.shape_red));
mStateListDrawable.addState(new int[]{android.R.attr.state_pressed}, getDrawable(R.drawable.shape_white));
mStateListDrawable.addState(new int[]{android.R.attr.state_selected}, getDrawable(R.drawable.shape_red));
mStateListDrawable.addState(new int[]{},getDrawable(R.drawable.shape_white));//默认
image.setBackground(mStateListDrawable);
LevelListDrawable原理同上，xml实例：
<?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>
LevelDrawable默认的level值为0，若是没有和0匹配的level，那么就不显示Drawable。level匹配以maxLevel值优先。例如：若是有个item1：minLevel：1，maxLevel：2,item2:minLevel：2，maxLevel：3。 mLevelDrawable.setLevel(2);那么会匹配第一个item1。代码调用实例以下：
@SuppressLint("NewApi")
private Drawable getLevelListDrawable() {
// TODO Auto-generated method stub
LevelListDrawable mLevelListDrawable=new LevelListDrawable();
mLevelListDrawable.addLevel(1, 2, getDrawable(R.drawable.shape_red));
mLevelListDrawable.addLevel(2, 3, getDrawable(R.drawable.shape_white));
mLevelListDrawable.setLevel(2);
return mLevelListDrawable;
}
TransitionDrawable是LayerDrawable的直接子类，公开动画startTransition(int duration)方法,源码以下：
/** * Begin the second layer on top of the first layer. * * @param durationMillis The length of the transition in milliseconds */
public void startTransition(int durationMillis) {
mFrom = 0;
mTo = 255;
mAlpha = 0;
mDuration = mOriginalDuration = durationMillis;
mReverse = false;
mTransitionState = TRANSITION_STARTING;
invalidateSelf();
}
这里提供一个图片加载的渐变效果以下：
private void fadeInDisplay(ImageView imageView, Bitmap bitmap) {
final TransitionDrawable transitionDrawable = new TransitionDrawable(
new Drawable[] { TRANSPARENT_DRAWABLE,
new BitmapDrawable(imageView.getResources(), bitmap) });
imageView.setBackground(transitionDrawable);
transitionDrawable.startTransition(200);
}
private static final ColorDrawable TRANSPARENT_DRAWABLE = new ColorDrawable(
android.R.color.transparent);
InsetDrawable也有和LayerDrawable类似的属性，构造方法：
public InsetDrawable(Drawable drawable, int inset) {
this(drawable, inset, inset, inset, inset);
}
public InsetDrawable(Drawable drawable, int insetLeft, int insetTop,
int insetRight, int insetBottom) {
this(null, null);
}
private InsetDrawable(InsetState state, Resources res) {
mState = new InsetState(state, this, res);
}
final static class InsetState extends ConstantState {
....
}
下面是代码调用和xml实例
InsetDrawable mInsetDrawable=new InsetDrawable(getDrawable(R.drawable.shape_red), 20, 30, 30, 20);
<?xml version="1.0" encoding="utf-8"?>
<inset xmlns:android="http://schemas.android.com/apk/res/android" android:drawable="@drawable/shape_red" android:insetTop="10dp" android:insetRight="10dp" android:insetLeft="10dp" />
ClipDrawable就比较有意思了，能够用来制做图片进度，动态setLevel()控制图片块的显示，xml实例：
<?xml version="1.0" encoding="utf-8"?>
<clip xmlns:android="http://schemas.android.com/apk/res/android" android:drawable="@drawable/ic_launcher" android:clipOrientation="horizontal" android:gravity="left" />
new ClipDrawable传入参数orientation参照：ClipDrawable.HORIZONTAL/VERTICAL.当level为0时，截取的图片片断为空；当level为10000时，截取整张图片.下面是代码调用实例：
ClipDrawable mClipDrawable=new ClipDrawable(getDrawable(R.drawable.ic_launcher), Gravity.CENTER, ClipDrawable.HORIZONTAL);
image.setImageDrawable(mClipDrawable);
image.setLevel(100);
ScaleDrawable对于drawable资源进行尺寸变换，xml调用实例：
<?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%" />
ScaleDrawable构造方法
public ScaleDrawable(Drawable drawable, int gravity, float scaleWidth, float scaleHeight) {
this(null, null);
mState.mDrawable = drawable;
mState.mGravity = gravity;
mState.mScaleWidth = scaleWidth;
mState.mScaleHeight = scaleHeight;
if (drawable != null) {
drawable.setCallback(this);
}
}
代码调用实例：
ScaleDrawable mScaleDrawable=new ScaleDrawable(drawable, gravity, scaleWidth, scaleHeight);
mScaleDrawable.setLevel(1);//leve=0时，Drawable资源不可见
AnimationDrawable可用于播放帧动画，官方提供的animation-list.xml调用实例：
<animation-list android:id="@+id/selected" android:oneshot="false">
<item android:drawable="@drawable/wheel0" android:duration="50" />
<item android:drawable="@drawable/wheel1" android:duration="50" />
<item android:drawable="@drawable/wheel2" android:duration="50" />
<item android:drawable="@drawable/wheel3" android:duration="50" />
<item android:drawable="@drawable/wheel4" android:duration="50" />
<item android:drawable="@drawable/wheel5" android:duration="50" />
</animation-list>
在activity里面或AnimationDrawable实例后调用start方法便可，须要注意的是在onCreate方法里面最好不调用start,代码调用实例：
@Override
public void onWindowFocusChanged(boolean hasFocus) {
// TODO Auto-generated method stub
super.onWindowFocusChanged(hasFocus);
mAnimationDrawable=new AnimationDrawable();
mAnimationDrawable.addFrame(getDrawable(R.drawable.shape_red), 1000);
mAnimationDrawable.addFrame(getDrawable(R.drawable.shape_white), 2000);
image.setImageDrawable(mAnimationDrawable);
if(hasFocus){
mAnimationDrawable.start();
}
}
RotateDrawable可旋转的Drawable,在应用里面相机拍照后获取保留下来的图片多是反向的，这里就能够用RotateDrawable旋转角度，setFromDegrees 、setToDegrees控制旋转角度，setPivotY 、setPivotX控制旋转的轴，好比（50%，50%）中心旋转，下面是调用的相关实例：
<?xml version="1.0" encoding="utf-8"?>
<rotate xmlns:android="http://schemas.android.com/apk/res/android" android:drawable="@drawable/image" android:visible="true" android:fromDegrees="0" android:toDegrees="180" android:pivotX="50%" android:pivotY="50%">
</rotate>
ShapeDrawable 这个就比较熟悉了，咱们经常使用shape绘制图形纯色背景，规则以下：
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape=["rectangle" | "oval" | "line" | "ring"] >
<corners android:radius="integer" android:topLeftRadius="integer" android:topRightRadius="integer" android:bottomLeftRadius="integer" android:bottomRightRadius="integer" />
<gradient android:angle="integer" android:centerX="integer" android:centerY="integer" android:centerColor="integer" android:endColor="color" android:gradientRadius="integer" android:startColor="color" android:type=["linear" | "radial" | "sweep"] android:useLevel=["true" | "false"] />
<padding android:left="integer" android:top="integer" android:right="integer" android:bottom="integer" />
<size android:width="integer" android:height="integer" />
<solid android:color="color" />
<stroke android:width="integer" android:color="color" android:dashWidth="integer" android:dashGap="integer" />
</shape>
此处解析标签以下：
/** * Subclasses override this to parse custom subelements. If you handle it, * return true, else return <em>super.inflateTag(...)</em>. */
protected boolean inflateTag(String name, Resources r, XmlPullParser parser,
AttributeSet attrs) {
if ("padding".equals(name)) {
TypedArray a = r.obtainAttributes(attrs,
com.android.internal.R.styleable.ShapeDrawablePadding);
setPadding(
a.getDimensionPixelOffset(
com.android.internal.R.styleable.ShapeDrawablePadding_left, 0),
a.getDimensionPixelOffset(
com.android.internal.R.styleable.ShapeDrawablePadding_top, 0),
a.getDimensionPixelOffset(
com.android.internal.R.styleable.ShapeDrawablePadding_right, 0),
a.getDimensionPixelOffset(
com.android.internal.R.styleable.ShapeDrawablePadding_bottom, 0));
a.recycle();
return true;
}
return false;
}
此处解析width 、height、color、dither等相关属性
private void updateStateFromTypedArray(TypedArray a) {
final ShapeState state = mShapeState;
final Paint paint = state.mPaint;
// Account for any configuration changes.
state.mChangingConfigurations |= a.getChangingConfigurations();
// Extract the theme attributes, if any.
state.mThemeAttrs = a.extractThemeAttrs();
int color = paint.getColor();
color = a.getColor(R.styleable.ShapeDrawable_color, color);
paint.setColor(color);
boolean dither = paint.isDither();
dither = a.getBoolean(R.styleable.ShapeDrawable_dither, dither);
paint.setDither(dither);
setIntrinsicWidth((int) a.getDimension(
R.styleable.ShapeDrawable_width, state.mIntrinsicWidth));
setIntrinsicHeight((int) a.getDimension(
R.styleable.ShapeDrawable_height, state.mIntrinsicHeight));
final int tintMode = a.getInt(R.styleable.ShapeDrawable_tintMode, -1);
if (tintMode != -1) {
state.mTintMode = Drawable.parseTintMode(tintMode, Mode.SRC_IN);
}
final ColorStateList tint = a.getColorStateList(R.styleable.ShapeDrawable_tint);
if (tint != null) {
state.mTint = tint;
}
}
ShapeDrawable构造方法：
/** * ShapeDrawable constructor. */
public ShapeDrawable() {
this(new ShapeState(null), null);
}
/** * Creates a ShapeDrawable with a specified Shape. * * @param s the Shape that this ShapeDrawable should be */
public ShapeDrawable(Shape s) {
this(new ShapeState(null), null);
mShapeState.mShape = s;
}
/** * The one constructor to rule them all. This is called by all public * constructors to set the state and initialize local properties. */
private ShapeDrawable(ShapeState state, Resources res) {
mShapeState = state;
initializeWithState(state, res);
}
ShapeDrawa实例化的时候new了一个ShapeState,绑定了ShaderFactory， public abstract Shader resize(int width, int height);该方法在setShape 、onBoundsChange是会调用，从新测量，代码以下：
private void updateShape() {
if (mShapeState.mShape != null) {
final Rect r = getBounds();
final int w = r.width();
final int h = r.height();
mShapeState.mShape.resize(w, h);
if (mShapeState.mShaderFactory != null) {
mShapeState.mPaint.setShader(mShapeState.mShaderFactory.resize(w, h));
}
}
invalidateSelf();
}
下面是onDraw调用：
@Override
public void draw(Canvas canvas) {
final Rect r = getBounds();
final ShapeState state = mShapeState;
final Paint paint = state.mPaint;
final int prevAlpha = paint.getAlpha();
paint.setAlpha(modulateAlpha(prevAlpha, state.mAlpha));
// only draw shape if it may affect output
if (paint.getAlpha() != 0 || paint.getXfermode() != null || paint.hasShadowLayer()) {
final boolean clearColorFilter;
if (mTintFilter != null && paint.getColorFilter() == null) {
paint.setColorFilter(mTintFilter);
clearColorFilter = true;
} else {
clearColorFilter = false;
}
if (state.mShape != null) {
// need the save both for the translate, and for the (unknown)
// Shape
final int count = canvas.save();
canvas.translate(r.left, r.top);
onDraw(state.mShape, canvas, paint);
canvas.restoreToCount(count);
} else {
canvas.drawRect(r, paint);
}
if (clearColorFilter) {
paint.setColorFilter(null);
}
}
// restore
paint.setAlpha(prevAlpha);
}
经过ShapeState获取画笔，先判断是否须要清除colorFilter,然会根据shape进行绘制，paint从新赋值。开发中通常都在使用shape绘制纯色背景块，经过selector控制shape显示.还有更多Drawable子类这里就不列举了，看了Drawable系列的相关资料后，萌生出了这么一种想法，经过工厂，直接形成本身想要的Drawable资源，传入简单的参数就能够了，再也不用每次都写Drawable.xml文件 ,下面是个简要思路：
public class DrawableFactory {
............此处省略..................
public static final int DRAWABLE_SHAPE=0;
public Drawable getDrawable(DrawableType mType,OnBasicDrawableListener onBasicDrawableListener){
Drawable mDrawable=null;
switch (mType.getTypeValue()) {
case DRAWABLE_SHAPE:
mDrawable=ShapeDrawableHelper.getInstance(mContext).getDrawable(onBasicDrawableListener);
break;
default:
break;
}
return mDrawable;
}
}
根据传入不一样的Drawable类型，判断选择不一样的helper类，经过getDrawable获取Drawable，不一样的Drawable实例所须要的参数经过onBasicDrawableListener定义的方法获取。以上就是我看了Drawable相关资料的收获，这里作个记录分享。