Android利用Paint自定义View实现进度条控件方法示例

前言

View的三大流程：测量，布局，绘制，自定义View学的是啥？无非就两种：绘制文字和绘制图像。

我们在上一篇文章《Android绘图之Paint的使用》中学习了Paint的基本用法，但是具体的应用我们还没有实践过。从标题中可知，本文是带领读者使用Paint，自定义一个进度条控件。

效果图

上图就是本文要实现的效果图。

实现过程

既然是自定义控件，本文的该控件是直接继承View，然后重写View的onMeasure和onDraw方法来实现。其中onMeasure主要作用是测量控件的宽/高。而onDraw则是将界面绘制到屏幕上。

从效果的效果上看，我们需要自定义一些属性，如：进度度条的颜色、圆边框的颜色、圆边框的宽度和文本的大小等等。
具体的自定义属性请看下面attrs.xml的代码：

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <declare-styleable name="CustomProgressBar">
 <attr name="roundProgressColor" format="color"></attr>
 <attr name="roundColor" format="color"></attr>
 <attr name="roundWidth" format="dimension"></attr>
 <attr name="textSize" format="dimension"></attr>
 <attr name="textColor" format="color"></attr>
 <attr name="max" format="integer"></attr>
 <attr name="textShow" format="boolean"></attr>
 <attr name="style">
  <enum name="STROKE" value="0"></enum>
  <enum name="FILL" value="1"></enum>
 </attr>
 </declare-styleable>
</resources>

接下来看本文的最重要部分，也就是自定义View

public class CustomProgressBar extends View {

 private int max = 100;//总进度
 private int roundColor = Color.RED;//进度圆弧的颜色
 private float roundWidth = 10;//圆边框宽度
 private int roundProgressColor = Color.BLUE;//默认的大圆环边框颜色
 private float textSize = 55;//文本大小
 private int textColor = Color.GREEN;//文本默认颜色
 private boolean textShow = true;//是否展示文本
 public static final int STROKE = 0;//描边
 public static final int FILL = 1;//填充
 private int style = STROKE;//默认描边

 private int progress;//进度
 private Paint mPaint;

 private int mWidth = 200;//默认控件宽度，wrap_content时候使用
 private int mHeight = 200;//默认控件高度，wrap_content时候使用

 public CustomProgressBar(Context context) {
 this(context, null);
 }

 public CustomProgressBar(Context context, @Nullable AttributeSet attrs) {
 super(context, attrs);
 init(context, attrs);
 }

 private void init(Context context, AttributeSet attrs) {
 mPaint = new Paint();
 if (attrs != null) {
  TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.CustomProgressBar);
  max = typedArray.getInteger(R.styleable.CustomProgressBar_max, 100);
  roundColor = typedArray.getColor(R.styleable.CustomProgressBar_roundColor, Color.BLUE);
  roundProgressColor = typedArray.getColor(R.styleable.CustomProgressBar_roundProgressColor, Color.BLUE);
  textColor = typedArray.getColor(R.styleable.CustomProgressBar_textColor, Color.GREEN);
  textSize = typedArray.getDimension(R.styleable.CustomProgressBar_textSize, 55);
  roundWidth = typedArray.getDimension(R.styleable.CustomProgressBar_roundWidth, 10);
  textShow = typedArray.getBoolean(R.styleable.CustomProgressBar_textShow, true);
  style = typedArray.getInt(R.styleable.CustomProgressBar_style, 0);

  typedArray.recycle();
 }
 }

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 super.onMeasure(widthMeasureSpec, heightMeasureSpec);
 int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);
 int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
 int heightSpecSize = MeasureSpec.getSize(heightMeasureSpec);
 int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
 if (widthSpecMode == MeasureSpec.AT_MOST && heightSpecMode == MeasureSpec.AT_MOST){
  setMeasuredDimension(mWidth,mHeight);
 }else if (widthSpecMode == MeasureSpec.AT_MOST){
  setMeasuredDimension(mWidth,heightSpecSize);
 }else if (heightSpecMode == MeasureSpec.AT_MOST){
  setMeasuredDimension(widthSpecSize,mHeight);
 }
 }

 @Override
 protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);

 final int paddingLeft = getPaddingLeft();
 final int paddingRight = getPaddingRight();
 final int paddingTop = getPaddingTop();
 final int paddingBottom = getPaddingBottom();
 int width = getWidth() - paddingLeft - paddingRight;
 int height = getHeight() - paddingBottom - paddingTop;

 //画默认的大圆环
 float radius = (float)Math.min(width,height)/2.0f;//中心坐标点
 mPaint.setColor(roundColor);
 mPaint.setStyle(Paint.Style.STROKE);//描边
 mPaint.setStrokeWidth(roundWidth);//圆环边的宽度
// if (style == STROKE){
//  mPaint.setStrokeWidth(roundWidth);//圆环边的宽度
// }
 mPaint.setAntiAlias(true);
 //(float cx, float cy, float radius, @NonNull Paint paint)
 canvas.drawCircle(paddingLeft+width/2,paddingTop+height/2,radius,mPaint);

 //画进度百分比
 mPaint.setColor(textColor);
 mPaint.setStrokeWidth(0);//圆环的宽度
 mPaint.setTextSize(textSize);
 mPaint.setTypeface(Typeface.DEFAULT_BOLD);

 int percent = (int)(progress/(float)max * 100);
 if(textShow && percent!=0 && style == STROKE){
  //(@NonNull String text, float x, float y, @NonNull Paint paint)
  canvas.drawText(percent+"%", (getWidth()-mPaint.measureText(percent+"%"))/2f,
   //y公式： float baselineY = centerY + (fontMetrics.bottom-fontMetrics.top)/2 - fontMetrics.bottom
   getWidth()/2f-(mPaint.descent()+mPaint.ascent())/2f,
   mPaint);
 }

 //画圆弧
 //矩形区域，定义圆弧的形状大小
 //(float left, float top, float right, float bottom)
 RectF oval = new RectF(paddingLeft, paddingTop, width+paddingLeft, height+paddingTop);
 mPaint.setColor(roundProgressColor);
 mPaint.setStrokeWidth(roundWidth);//圆环边的宽度
 switch (style){
  case STROKE:
  mPaint.setStyle(Paint.Style.STROKE);
  //(@NonNull RectF oval, float startAngle, float sweepAngle, boolean useCenter,@NonNull Paint paint)
  //useCenter:设置圆弧在绘画的时候，是否经过圆形
  canvas.drawArc(oval , 0, 360*progress/max, false, mPaint);
  break;
  case FILL:
  mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
  if(progress!=0)
   canvas.drawArc(oval , 0, 360*progress/max, true, mPaint);
  break;
  default:
  break;
 }

 }

 public void setProgressWidth(int width) {
 mWidth = width;
 }

 public void setProgressHeight(int height) {
 mHeight = height;
 }

 public synchronized void setMax(int max) {
 if (max < 0) {
  throw new IllegalArgumentException("max不能小于0");
 }
 this.max = max;
 }

 public void setRoundColor(int roundColor) {
 this.roundColor = roundColor;
 }

 public void setRoundWidth(float roundWidth) {
 this.roundWidth = roundWidth;
 }

 public void setRoundProgressColor(int roundProgressColor) {
 this.roundProgressColor = roundProgressColor;
 }

 public void setTextSize(float textSize) {
 this.textSize = textSize;
 }

 public void setTextColor(int textColor) {
 this.textColor = textColor;
 }

 public void setTextShow(boolean textShow) {
 this.textShow = textShow;
 }

 public synchronized void setProgress(int progress) {
 if (progress < 0) {
  throw new IllegalArgumentException("progress不能小于0");
 }
 if (progress > max) {
  progress = max;
 }
 if (progress <= max) {
  this.progress = progress;
  postInvalidate();
 }
 }

 public synchronized int getMax() {
 return max;
 }

 public int getRoundColor() {
 return roundColor;
 }

 public float getRoundWidth() {
 return roundWidth;
 }

 public int getRoundProgressColor() {
 return roundProgressColor;
 }

 public int getTextColor() {
 return textColor;
 }

 public boolean isTextShow() {
 return textShow;
 }

 public synchronized int getProgress() {
 return progress;
 }
}

流程：初始化的时候会拿到自定义属性，然后onMeasure方法中测量控件的宽和高，该方法主要处理了LayoutParams的wrap_content，当wrap_content时，默认设置默认宽/高，而不是让控件占据整个屏幕，需要调用setMeasuredDimension方法测量。最后测量得到了控件的宽/高，调用onDraw方法将界面绘制到屏幕上，在onDraw方法绘制的时需要考虑padding的情况，如果不做padding处理，则padding将不起作用。

onDraw绘制流程：先绘制一个默认的大圆环，然后在圆中心绘制百分比的文本，最后再绘制一个进度圆环，进度圆环会覆盖底部的默认大圆环，这样就达到显示进度的情况。

设置好画笔之后，使用canvas.drawCircle绘制默认的大圆环，再次设置画笔，使用canvas.drawText方法绘制文本；画圆弧时需要定义一个矩形区域RectF，通过canvas.drawArc方法绘制。

绘制好之后，如何让用户看到进度条在变化呢？其实就是通过setProgress方法里面的postInvalidate()方法，该方法会刷新界面，刷新界面时会调用onDraw，这样就可以将进度画到屏幕上，进度条不停的在变化。

使用

XML中使用

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 tools:context="com.main.paint.PaintActivity">

 <com.main.paint.CustomProgressBar
 android:id="@+id/progressbar"
 android:layout_width="200dp"
 android:layout_height="200dp"
 app:roundProgressColor="#FF0000"
 app:roundWidth="2dp"
 app:textColor="#FF0000"
 app:style="STROKE"
 android:padding="30dp"
 app:textSize="20dp"/>

 <com.main.paint.CustomProgressBar
 android:id="@+id/progressbar01"
 android:layout_width="200dp"
 android:layout_height="200dp"
 app:roundProgressColor="#FF0000"
 app:roundWidth="2dp"
 app:textColor="#FF0000"
 app:style="FILL"
 android:padding="30dp"
 app:textSize="20dp"/>

</LinearLayout>

Activity代码如下：

public class PaintActivity extends AppCompatActivity {

 private CustomProgressBar mCustomProgressBar;
 private CustomProgressBar mCustomProgressBar01;
 private int progress;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_paint);
 mCustomProgressBar = (CustomProgressBar)this.findViewById(R.id.progressbar);
 mCustomProgressBar.setOnClickListener(new View.OnClickListener() {

  @Override
  public void onClick(View v) {
  new Thread(new Runnable() {

   @Override
   public void run() {
   progress = 0;
   while (progress <= 100) {
    progress += 2;
    mCustomProgressBar.setProgress(progress);
    try {
    Thread.sleep(100);
    } catch (InterruptedException e) {
    e.printStackTrace();
    }
   }
   }
  }).start();
  }
 });

 mCustomProgressBar01 = (CustomProgressBar)this.findViewById(R.id.progressbar01);
 mCustomProgressBar01.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  new Thread(new Runnable() {

   @Override
   public void run() {
   progress = 0;
   while (progress <= 100) {
    progress += 2;
    mCustomProgressBar01.setProgress(progress);
    try {
    Thread.sleep(100);
    } catch (InterruptedException e) {
    e.printStackTrace();
    }
   }
   }
  }).start();
  }
 });
 }
}

这样就完成了一个自定义的进度条控件，并且在onDraw方法中使用Paint将界面绘制出来。读者可以自行实践一把，加深对Paint的理解。

总结

以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作具有一定的参考学习价值，如果有疑问大家可以留言交流，谢谢大家对我们的支持。