前言
该篇文章根据前面 重学 Android 自定义 View 系列(六):环形进度条 拓展而来。
最终效果如下:
1. 扩展功能
- 支持进度顺时针或逆时针显示
- 在进度条末尾添加自定义指针图片
- 使用线性渐变为进度条添加颜色效果
2. 关键技术点解析
2.1 进度方向控制的实现
通过添加一个 direction 属性,设置角度的正负,决定进度条是顺时针还是逆时针绘制:
public static final int CLOCKWISE = 1;
public static final int COUNTERCLOCKWISE = -1;
private int direction = COUNTERCLOCKWISE; // 默认逆时针
// 在 onDraw 方法中计算扫过的角度时,加入方向
float sweepAngle = 360f * progress / maxProgress;
sweepAngle *= direction;
// 绘制进度条
canvas.drawArc(rectF, startAngle, sweepAngle, false, progressPaint);
2.2 自定义指针图片的绘制
在环形进度条的末尾,绘制一张 Bitmap 图片作为指针,图片可由你传入,但指针的方向要和demo中的一致,如下:
绘制指针的步骤:
- 调整指针的绘制半径:确保指针贴合圆环外侧,加入一个 outerSize 参数用于控制指针漏出圆环的长度。
- 计算指针位置:使用三角函数计算图片中心点坐标。
- 旋转画布并绘制图片(关键):将画布旋转到指定角度后,再绘制指针图片。
用到的三角函数原理如下,再重温一下学校的知识:),因为在Java中 Math 函数计算三角函数用的是弧度而不是角度,所以代码使用了Math.toRadians
进行了角度转弧度。
核心代码实现:
private void drawPointer(Canvas canvas, float angle) {
// 调整半径,使指针图片紧贴圆环外部
float adjustedRadius = radius + backgroundPaint.getStrokeWidth() / 2 + outerSize;
// 计算指针的中心点位置
float rightCenterX = centerX + adjustedRadius * (float) Math.cos(Math.toRadians(angle));
float rightCenterY = centerY + adjustedRadius * (float) Math.sin(Math.toRadians(angle));
// 计算Bitmap左上角位置
float left = rightCenterX - bitmapWidth;
float top = rightCenterY - bitmapHeight / 2;
// 保存画布状态,旋转画布
canvas.save();
canvas.rotate(angle, rightCenterX, rightCenterY);
// 绘制指针Bitmap
canvas.drawBitmap(pointerBitmap, left, top, null);
// 恢复画布状态
canvas.restore();
}
重点是角度的计算 angle = startAngle + sweepAngle
,和指针的位移与旋转,结合三角函数计算坐标,并通过旋转画布保持图片对齐,使指针始终指向圆心位置。
2.3 渐变颜色的实现
为进度条添加线性渐变效果使用了 LinearGradient 着色器,实际效果按需求自定义,重点是 计算渐变起点和终点,因为有起始角度的存在,需要用到 圆心坐标、半径和起始角度计算:
private void updateGradient() {
// 计算圆上的起点和终点坐标
double startAngleRadians = Math.toRadians(startAngle);
float startX = centerX + (float) (radius * Math.cos(startAngleRadians));
float startY = centerY + (float) (radius * Math.sin(startAngleRadians));
float endX = centerX - (float) (radius * Math.cos(startAngleRadians));
float endY = centerY - (float) (radius * Math.sin(startAngleRadians));
//线性渐变,从一个点渐变到另一个点,因为渐变的距离是圆的直径 所以,TileMode 在这里实际无意义
gradientShader = new LinearGradient(
startX, startY, endX, endY,
progressColors, null,
Shader.TileMode.CLAMP
);
progressPaint.setShader(gradientShader);
}
4. 定义自定义属性
<declare-styleable name="CircularProgressBarEx">
<!-- 进度条的最大值 -->
<attr name="maxProgress" format="integer"/>
<!-- 当前进度 -->
<attr name="progress" format="integer"/>
<!-- 环形进度条的背景色 -->
<attr name="circleBackgroundColor" format="color"/>
<!-- 进度条的颜色 -->
<attr name="progressColor" format="color"/>
<!-- 进度条的宽度 -->
<attr name="circleWidth" format="dimension"/>
<!-- 显示进度文本 -->
<attr name="showProgressText" format="boolean"/>
<!-- 进度文本的颜色 -->
<attr name="progressTextColor" format="color"/>
<!-- 进度文本的大小 -->
<attr name="progressTextSize" format="dimension"/>
<!-- 开始角度 -->
<attr name="startAngle" format="enum">
<enum name="angle0" value="0"/>
<enum name="angle90" value="90"/>
<enum name="angle180" value="180"/>
<enum name="angle270" value="270"/>
</attr>
<!-- 进度方向 -->
<attr name="direction">
<enum name="clockwise" value="1"/>
<enum name="counterclockwise" value="-1"/>
</attr>
<!-- 指针漏出的长度 -->
<attr name="outerSize" format="dimension"/>
</declare-styleable>
5. 完整代码
public class CircularProgressBarEx extends View {
private Paint backgroundPaint;
private Paint progressPaint;
private Paint textPaint;
private RectF rectF;
private Bitmap pointerBitmap; // 指针图标
private float bitmapWidth; // Bitmap的宽度
private float bitmapHeight; // Bitmap的高度
private int outerSize = 5; //让指针漏出圆环的长度
private int maxProgress = 100;
private int progress = 0;
private int circleBackgroundColor = Color.GRAY;
private int[] progressColors = {Color.GREEN, Color.BLUE}; // 渐变颜色
private int circleWidth = 20;
private boolean showProgressText = true;
private int progressTextColor = Color.BLACK;
private int progressTextSize = 50;
private int startAngle = 0; // 默认从左边开始
private float centerX, centerY;
private float radius;
public static final int CLOCKWISE = 1;
public static final int COUNTERCLOCKWISE = -1;
private int direction = COUNTERCLOCKWISE; // 默认顺时针
private LinearGradient gradientShader;
public CircularProgressBarEx(Context context) {
this(context, null);
}
public CircularProgressBarEx(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public CircularProgressBarEx(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
if (attrs != null) {
TypedArray typedArray = context.getTheme().obtainStyledAttributes(
attrs,
R.styleable.CircularProgressBarEx,
0, 0
);
try {
maxProgress = typedArray.getInt(R.styleable.CircularProgressBarEx_maxProgress, 100);
progress = typedArray.getInt(R.styleable.CircularProgressBarEx_progress, 0);
circleBackgroundColor = typedArray.getColor(R.styleable.CircularProgressBarEx_circleBackgroundColor, Color.GRAY);
circleWidth = typedArray.getDimensionPixelSize(R.styleable.CircularProgressBarEx_circleWidth, 20);
showProgressText = typedArray.getBoolean(R.styleable.CircularProgressBarEx_showProgressText, true);
progressTextColor = typedArray.getColor(R.styleable.CircularProgressBarEx_progressTextColor, Color.BLACK);
progressTextSize = typedArray.getDimensionPixelSize(R.styleable.CircularProgressBarEx_progressTextSize, 50);
startAngle = typedArray.getInt(R.styleable.CircularProgressBarEx_startAngle, 0);
direction = typedArray.getInt(R.styleable.CircularProgressBarEx_direction, CLOCKWISE);
outerSize = typedArray.getDimensionPixelSize(R.styleable.CircularProgressBarEx_outerSize, 5);
} finally {
typedArray.recycle();
}
}
backgroundPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
backgroundPaint.setColor(circleBackgroundColor);
backgroundPaint.setStyle(Paint.Style.STROKE);
backgroundPaint.setStrokeWidth(circleWidth);
progressPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
progressPaint.setStyle(Paint.Style.STROKE);
progressPaint.setStrokeWidth(circleWidth);
//progressPaint.setStrokeCap(Paint.Cap.ROUND);
textPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
textPaint.setColor(progressTextColor);
textPaint.setTextSize(progressTextSize);
textPaint.setTextAlign(Paint.Align.CENTER);
rectF = new RectF();
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
int padding = circleWidth / 2 + outerSize;
rectF.set(padding, padding, w - padding, h - padding);
centerX = rectF.centerX();
centerY = rectF.centerY();
radius = rectF.width() / 2;
updateGradient();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// 绘制背景圆环
//canvas.drawArc(rectF, 0f, 360f, false, backgroundPaint);
// 绘制背景圆环
canvas.drawCircle(centerX, centerY, radius, backgroundPaint);
// 计算进度角度
float sweepAngle = 360f * progress / maxProgress;
sweepAngle *= direction;
// 绘制进度
canvas.drawArc(rectF, startAngle, sweepAngle, false, progressPaint);
// 绘制进度文本
if (showProgressText) {
String progressText = progress + "%";
float x = getWidth() / 2f;
float y = getHeight() / 2f - (textPaint.descent() + textPaint.ascent()) / 2f;
canvas.drawText(progressText, x, y, textPaint);
}
// 绘制指针
if (pointerBitmap != null) {
drawPointer(canvas, startAngle + sweepAngle);
}
}
/**
* 绘制指针
*
* @param angle 指针的角度(画布坐标系下的角度)
*/
private void drawPointer(Canvas canvas, float angle) {
//Log.d("drawPointer", "angle: " + angle);
// 计算调整后的半径,使Bitmap边缘紧贴圆环最外部
float adjustedRadius = radius + backgroundPaint.getStrokeWidth() / 2 + outerSize;
// 确保Bitmap的右边上的中心点在圆上
float rightCenterX = centerX + adjustedRadius * (float) Math.cos(Math.toRadians(angle));
float rightCenterY = centerY + adjustedRadius * (float) Math.sin(Math.toRadians(angle));
// 计算Bitmap左上角的位置,使得右边上的中心点位于计算出的坐标
float left = rightCenterX - bitmapWidth;
float top = rightCenterY - bitmapHeight / 2;
// 保存画布状态
canvas.save();
// 将画布旋转,使得Bitmap对齐到半径上
canvas.rotate(angle, rightCenterX, rightCenterY);
// 绘制指针Bitmap
canvas.drawBitmap(pointerBitmap, left, top, null);
// 恢复画布状态
canvas.restore();
}
// 更新渐变
private void updateGradient() {
float centerX = rectF.centerX();
float centerY = rectF.centerY();
float radius = rectF.width() / 2;
double startAngleRadians = Math.toRadians(startAngle);
float startX = centerX + (float) (radius * Math.cos(startAngleRadians));
float startY = centerY + (float) (radius * Math.sin(startAngleRadians));
float endX = centerX - (float) (radius * Math.cos(startAngleRadians));
float endY = centerY - (float) (radius * Math.sin(startAngleRadians));
//Log.d("updateGradient", "startX: " + startX + ", startY: " + startY + ", endX: " + endX + ", endY: " + endY);
//线性渐变,从一个点渐变到另一个点,因为渐变的距离是圆的直径 所以,TileMode 在这里实际无意义
gradientShader = new LinearGradient(
startX, startY, endX, endY,
progressColors, null,
Shader.TileMode.CLAMP
);
progressPaint.setShader(gradientShader);
}
// 设置进度
public void setProgress(int progress) {
this.progress = Math.max(0, Math.min(progress, maxProgress));
invalidate();
}
// 设置指针图标
public void setPointerBitmap(Bitmap bitmap) {
this.pointerBitmap = bitmap;
bitmapWidth = bitmap.getWidth();
bitmapHeight = bitmap.getHeight();
invalidate();
}
// 设置渐变颜色
public void setProgressColors(int[] colors) {
this.progressColors = colors;
updateGradient();
invalidate();
}
// 设置绘制方向
public void setDirection(int direction) {
this.direction = direction;
invalidate();
}
// 设置开始角度
public void setStartAngle(int angle) {
this.startAngle = angle;
updateGradient();
invalidate();
}
// 获取当前进度
public int getProgress() {
return progress;
}
}
6. 使用示例
xml:
<com.xaye.diyview.view.progressEx.CircularProgressBarEx
android:id="@+id/circularProgressBar"
android:layout_width="140dp"
android:layout_height="140dp"
app:maxProgress="100"
app:circleBackgroundColor="#DDDDDD"
app:progressColor="#00B8D4"
app:circleWidth="15dp"
app:showProgressText="true"
app:progressTextColor="#000000"
app:progressTextSize="20sp"
app:startAngle="angle0"
app:direction="clockwise"
app:outerSize="10dp" />
Activity:
mBind.circularProgressBar.setPointerBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.point))
mBind.circularProgressBar2.setPointerBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.point))
mBind.circularProgressBar3.setPointerBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.point))
mBind.circularProgressBar4.setPointerBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.point))
mBind.btnStartAnimation.clickNoRepeat {
val animator = ValueAnimator.ofInt(0, 95)
animator.setDuration(2000)
animator.interpolator = LinearInterpolator()
animator.addUpdateListener { animation ->
val value = animation.animatedValue as Int
mBind.circularProgressBar.setProgress(value)
mBind.circularProgressBar2.progress = value
mBind.circularProgressBar3.progress = value
mBind.circularProgressBar4.progress = value
}
animator.start()
}
}
7. 最后
本篇文章由网友 Fas 的评论拓展而来,相比于之前那一篇还是稍稍有点难度的,哈哈。
源码及更多自定义View已上传Github:DiyView
另外给喜欢记笔记的同学安利一款好用的云笔记软件,对比大部分国内的这个算还不错的,免费好用:wolai