Andorid-Tint使用与原理解析

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Android Tint使用

Tint 属性

　　Tint 是 Android5.0 引入的一个属性，它可以在Android5.0 系统上，对视图进行颜色渲染。
下面是网上一个使用tint属性给背景调整不同颜色的例子：

 <LinearLayout          android:orientation="horizontal"          android:layout_width="wrap_content"          android:layout_height="wrap_content"          android:layout_gravity="center_horizontal">          <ImageView              ...              android:src="@drawable/xamarin_white"              android:background="@drawable/mycircle"/>          <ImageView              ...              android:src="@drawable/xamarin_white"              android:background="@drawable/mycircle"              android:tint="#2C3E50"/>          <ImageView              ...              android:src="@drawable/xamarin_white"              android:background="@drawable/mycircle"              android:tint="#B4BCBC"/>      </LinearLayout>

效果图：
此处输入图片的描述

　　tint这个属性，是ImageView有的，它可以给ImageView的src设置，除了tint 之外，还有backgroundTint,foregroundTint,drawableTint,它们分别对应对背景、前景、drawable进行着色处理。如果，我们给上面的例子设置 backgroundTint，那么蓝色背景就会被着色，替换成你设置的颜色。

原理

　　在5.0以上，View类中增加了对tint属性的获取

  case R.styleable.View_backgroundTint:                    // This will get applied later during setBackground().                    if (mBackgroundTint == null) {                        mBackgroundTint = new TintInfo();                    }                    mBackgroundTint.mTintList = a.getColorStateList(                            R.styleable.View_backgroundTint);                    mBackgroundTint.mHasTintList = true;                    break;case R.styleable.View_backgroundTintMode:    // This will get applied later during setBackground().    if (mBackgroundTint == null) {        mBackgroundTint = new TintInfo();    }    mBackgroundTint.mTintMode = Drawable.parseTintMode(a.getInt(            R.styleable.View_backgroundTintMode, -1), null);    mBackgroundTint.mHasTintMode = true;    break;

以具体的 ImageView 为例

//在构造函数中调用了这个方法private void applyImageTint() {        if (mDrawable != null && (mHasDrawableTint || mHasDrawableTintMode)) {            mDrawable = mDrawable.mutate();            if (mHasDrawableTint) {                mDrawable.setTintList(mDrawableTintList);            }            if (mHasDrawableTintMode) {                mDrawable.setTintMode(mDrawableTintMode);            }            // The drawable (or one of its children) may not have been            // stateful before applying the tint, so let's try again.            if (mDrawable.isStateful()) {                mDrawable.setState(getDrawableState());            }        }

setTintList 方法的实现

public void setTintList(ColorStateList tint) {        mBitmapState.mTint = tint;        mTintFilter = updateTintFilter(mTintFilter, tint, mBitmapState.mTintMode);        invalidateSelf();    }

当追踪到 updateTintFilter（）这个方法的时候，我们就无法继续向下追踪了，不过研究参数也可以得出它实现的方式(PorterDuffColorFilter,BitmapDrawable.BitmapState,PorterDuff.Mode), 很明显，还是利用的PorterDuff那些相关类来实现的操作，ProterDuff 网上也有很多说明的例子，最重要的还是下图：有关这些Mode的详细解释，大家自行查阅
此处输入图片的描述

版本问题

Tint在默认只在Android5.0以上的系统生效，为了向下支持，系统提供了相应的Compact类，包括
AppCompatTextView、AppCompatImageView等。我们使用 ViewCompat.setBackgroundTintMode 在懂吗中动态的为 View 进行tint 操作，观察这些Compat类发现都实现了 TintableBackgroundView 这个接口，如果需要让自定义的 View实现tint功能，我们可以仿照系统的实现类来实现。

/* * Copyright (C) 2014 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package android.support.v4.view;import android.content.res.ColorStateList;import android.graphics.PorterDuff;import android.support.annotation.Nullable;/** * Interface which allows a {@link android.view.View} to receive background tinting calls from * {@code ViewCompat} when running on API v20 devices or lower. */public interface TintableBackgroundView {    /**     * Applies a tint to the background drawable. Does not modify the current tint     * mode, which is {@link PorterDuff.Mode#SRC_IN} by default.     * <p>     * Subsequent calls to {@code View.setBackground(Drawable)} will automatically     * mutate the drawable and apply the specified tint and tint mode.     *     * @param tint the tint to apply, may be {@code null} to clear tint     *     * @see #getSupportBackgroundTintList()     */    void setSupportBackgroundTintList(@Nullable ColorStateList tint);    /**     * Return the tint applied to the background drawable, if specified.     *     * @return the tint applied to the background drawable     */    @Nullable    ColorStateList getSupportBackgroundTintList();    /**     * Specifies the blending mode used to apply the tint specified by     * {@link #setSupportBackgroundTintList(ColorStateList)}} to the background     * drawable. The default mode is {@link PorterDuff.Mode#SRC_IN}.     *     * @param tintMode the blending mode used to apply the tint, may be     *                 {@code null} to clear tint     * @see #getSupportBackgroundTintMode()     */    void setSupportBackgroundTintMode(@Nullable PorterDuff.Mode tintMode);    /**     * Return the blending mode used to apply the tint to the background     * drawable, if specified.     *     * @return the blending mode used to apply the tint to the background     *         drawable     */    @Nullable    PorterDuff.Mode getSupportBackgroundTintMode();}

参考：http://www.open-open.com/lib/view/open1454052058573.html

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