Android實現歌詞漸變色和進度的效果

2020-01-02 07:00:11

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要用TextView使用漸變色，那我們就必須要了解LinearGradient（線性漸變）的用法。

LinearGradient的參數解釋

LinearGradient也稱作線性渲染，LinearGradient的作用是實現某一區域內顏色的線性漸變效果，看源碼你就知道他是shader的子類。

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它有兩個構造函數

public LinearGradient(float x0, float y0, float x1, float y1, int color0, int color1, Shader.TileMode tile)public LinearGradient (float x0, float y0, float x1, float y1, int[] colors, float[] positions, Shader.TileMode tile);

其中，參數x0表示漸變的起始點x坐標；參數y0表示漸變的起始點y坐標；參數x1表示漸變的終點x坐標；參數y1表示漸變的終點y坐標　；color0表示漸變開始顏色；color1表示漸變結束顏色；參數tile表示平鋪方式。

Shader.TileMode有3種參數可供選擇，分別為CLAMP、REPEAT和MIRROR：

CLAMP的作用是如果渲染器超出原始邊界范圍，則會復制邊緣顏色對超出范圍的區域進行著色

REPEAT的作用是在橫向和縱向上以平鋪的形式重復渲染位圖

MIRROR的作用是在橫向和縱向上以鏡像的方式重復渲染位圖

LinearGradient的簡單使用

先實現文字效果的水平漸變：

Shader shader_horizontal= new LinearGradient(btWidth/4, 0, btWidth, 0, Color.RED, Color.GREEN, Shader.TileMode.CLAMP);tv_text_horizontal.getPaint().setShader(shader_horizontal);

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再實現文字的垂直漸變效果：

Shader shader_vertical=new LinearGradient(0, btHeight/4, 0, btHeight, Color.RED, Color.GREEN, Shader.TileMode.CLAMP);tv_text_vertical.getPaint().setShader(shader_vertical);

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接下來來實現文字的顏色動態漸變效果：

import android.content.Context;import android.graphics.Canvas;import android.graphics.LinearGradient;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.Shader;import android.util.AttributeSet;import android.widget.TextView;/*** Created on 2016/3/13.*/public class GradientHorizontalTextView extends TextView {private LinearGradient mLinearGradient;private Matrix mGradientMatrix;//漸變矩陣private Paint mPaint;//畫筆private int mViewWidth = 0;//textView的寬private int mTranslate = 0;//平移量private boolean mAnimating = true;//是否動畫private int delta = 15;//移動增量public GradientHorizontalTextView(Context ctx){this(ctx,null);}public GradientHorizontalTextView(Context context, AttributeSet attrs) {super(context, attrs);}@Overrideprotected void onSizeChanged(int w, int h, int oldw, int oldh) {super.onSizeChanged(w, h, oldw, oldh);if (mViewWidth == 0) {mViewWidth = getMeasuredWidth();if (mViewWidth > 0) {mPaint = getPaint();String text = getText().toString();int size;if(text.length()>0){size = mViewWidth*2/text.length();}else{size = mViewWidth;}mLinearGradient = new LinearGradient(-size, 0, 0, 0,new int[] { 0x33ffffff, 0xffffffff, 0x33ffffff },new float[] { 0, 0.5f, 1 }, Shader.TileMode.CLAMP); //邊緣融合mPaint.setShader(mLinearGradient);//設置漸變mGradientMatrix = new Matrix();}}}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);if (mAnimating && mGradientMatrix != null) {float mTextWidth = getPaint().measureText(getText().toString());//獲得文字寬mTranslate += delta;//默認向右移動if (mTranslate > mTextWidth+1 || mTranslate<1) {delta = -delta;//向左移動}mGradientMatrix.setTranslate(mTranslate, 0);mLinearGradient.setLocalMatrix(mGradientMatrix);postInvalidateDelayed(30);//刷新}}}

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實現歌詞進度效果

Canvas 作為繪制文本時，使用FontMetrics對象，計算位置的坐標。它的思路和java.awt.FontMetrics的基本相同。
FontMetrics對象它以四個基本坐標為基準，分別為：

FontMetrics.top
FontMetrics.ascent
FontMetrics.descent
FontMetrics.bottom

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// FontMetrics對象FontMetrics fontMetrics = textPaint.getFontMetrics(); String text = "abcdefghijklmnopqrstu"; // 計算每一個坐標float baseX = 0; float baseY = 100; float topY = baseY + fontMetrics.top; float ascentY = baseY + fontMetrics.ascent; float descentY = baseY + fontMetrics.descent; float bottomY = baseY + fontMetrics.bottom;

下面是具體實現代碼：

import android.content.Context;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.PorterDuff;import android.graphics.PorterDuffXfermode;import android.graphics.RectF;import android.util.AttributeSet;import android.view.View;/*** Created on 2016/3/13.*/public class SongTextView extends View {private int postIndex;private Paint mPaint;private int delta = 15;private float mTextHeight;private float mTextWidth;private String mText="夢 里 面 看 我 七 十 二 變";private PorterDuffXfermode xformode;public SongTextView(Context ctx){this(ctx,null);}public SongTextView(Context context, AttributeSet attrs) {this(context, attrs, 0);}public SongTextView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);init();}public void init(){mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);xformode = new PorterDuffXfermode(PorterDuff.Mode.SRC_IN);mPaint.setColor(Color.CYAN);mPaint.setTextSize(60.0f);mPaint.setStyle(Paint.Style.FILL_AND_STROKE);mPaint.setXfermode(null);mPaint.setTextAlign(Paint.Align.LEFT);//文字精確高度Paint.FontMetrics fontMetrics = mPaint.getFontMetrics();mTextHeight = fontMetrics.bottom-fontMetrics.descent-fontMetrics.ascent;mTextWidth = mPaint.measureText(mText);}/***計算 控件的寬高*/@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {final int mWidth;final int mHeight;/*** 設置寬度*/int widthMode = MeasureSpec.getMode(widthMeasureSpec);int widthSize = MeasureSpec.getSize(widthMeasureSpec);if (widthMode == MeasureSpec.EXACTLY)// match_parent , accuratemWidth = widthSize;else{// 由圖片決定的寬int desireByImg = getPaddingLeft() + getPaddingRight()+ getMeasuredWidth();if (widthMode == MeasureSpec.AT_MOST)// wrap_contentmWidth = Math.min(desireByImg, widthSize);elsemWidth = desireByImg;}/**** 設置高度*/int heightMode = MeasureSpec.getMode(heightMeasureSpec);int heightSize = MeasureSpec.getSize(heightMeasureSpec);if (heightMode == MeasureSpec.EXACTLY)// match_parent , accuratemHeight = heightSize;else{int desire = getPaddingTop() + getPaddingBottom()+ getMeasuredHeight();if (heightMode == MeasureSpec.AT_MOST)// wrap_contentmHeight = Math.min(desire, heightSize);elsemHeight = desire;}setMeasuredDimension( mWidth, mHeight);}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);Bitmap srcBitmap = Bitmap.createBitmap(getMeasuredWidth(),getMeasuredHeight(), Bitmap.Config.ARGB_8888);Canvas srcCanvas = new Canvas(srcBitmap);srcCanvas.drawText(mText, 0, mTextHeight, mPaint);mPaint.setXfermode(xformode);mPaint.setColor(Color.RED);RectF rectF = new RectF(0,0,postIndex,getMeasuredHeight());srcCanvas.drawRect(rectF, mPaint);canvas.drawBitmap(srcBitmap, 0, 0, null);init();if(postIndex<mTextWidth){postIndex+=10;}else{postIndex=0;}postInvalidateDelayed(30);}}

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ProgressBar實現歌詞播放效果

然后接下來的這種歌詞播放進度效果是2張圖片實現的，忘記是哪個那里看來的，壓根以前也沒有想過還可以這么樣的實現。
只需要準備2張圖即可：

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<layer-list xmlns:android="http://schemas.android.com/apk/res/android"><itemandroid:id="@android:id/background"android:drawable="@drawable/normal" /><itemandroid:id="@android:id/progress"android:drawable="@drawable/grandient" /></layer-list>

看見沒就是2張圖片，一張作為背景圖一張作為進度圖，是不是感覺很神奇，然后放入ProgressBar

<ProgressBarandroid:id="@+id/pb1"style="@android:style/Widget.ProgressBar.Horizontal"android:layout_width="300dp"android:layout_height="40dp"android:max="100"android:maxHeight="2dp"android:minHeight="2dp"android:progress="20"android:progressDrawable="@drawable/m_progress_horizontal"android:secondaryProgress="30"android:visibility="gone"/>

再加上代碼動態改變progress就能實現進度的變化了：

ProgressBar pb1= (ProgressBar) findViewById(R.id.pb1);//設置滾動條可見setProgressBarIndeterminateVisibility(true);progress=pb1.getProgress();//獲取初始進度timer=new Timer();task=new TimerTask() {@Overridepublic void run() {progress+=10;if(progress>100){progress=0;}handler.sendEmptyMessage(0);}};timer.schedule(task,1000,300);

實現及進度的改變：

Handler handler=new Handler(){@Overridepublic void handleMessage(Message msg) {super.handleMessage(msg);pb1.setProgress(progress);}};@Overrideprotected void onDestroy() {super.onDestroy();timer=null;task=null;handler.removeCallbacksAndMessages(null);}

效果也是不錯的：

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