Android Tint使用

Tint 屬性

　　Tint 是 Android5.0 引入的一個屬性，它可以在Android5.0 系統上，對檢視進行顏色渲染。 
下面是網上一個使用tint屬性給背景調整不同顏色的例子：

 <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>  
 

效果圖： 

　　tint這個屬性，是ImageView有的，它可以給ImageView的src設定，除了tint 之外，還有backgroundTint,foregroundTint,drawableTint,它們分別對應對背景、前景、drawable進行著色處理。 如果，我們給上面的例子設定 backgroundTint，那麼藍色背景就會被著色，替換成你設定的顏色。

原理

　　在5.0以上，View類中增加了對tint屬性的獲取

  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;
 

以具體的 ImageView 為例

//在建構函式中呼叫了這個方法
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 方法的實現

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

當追蹤到 updateTintFilter（）這個方法的時候，我們就無法繼續向下追蹤了，不過研究引數也可以得出它實現的方式(PorterDuffColorFilter,BitmapDrawable.BitmapState,PorterDuff.Mode), 很明顯，還是利用的PorterDuff那些相關類來實現的操作，ProterDuff 網上也有很多說明的例子，最重要的還是下圖： 有關這些Mode的詳細解釋，大家自行查閱 

版本問題

Tint在預設只在Android5.0以上的系統生效，為了向下支援，系統提供了相應的Compact類，包括 
AppCompatTextView、AppCompatImageView等。我們使用 ViewCompat.setBackgroundTintMode 在懂嗎中動態的為 View 進行tint 操作，觀察 這些Compat類發現都實現了 TintableBackgroundView 這個介面，如果需要讓自定義的 View實現tint功能，我們可以仿照系統的實現類來實現。

/*
 * 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();
}