使用的是一个第三方库android-pathview主要是一个自己定义View——PathView。跟全部自己定义View一样，重写了三个构造方法。
而且终于调用三个參数的构造方法，在里面获取自己定义属性。
/**
* Default constructor.
*
* @param context The Context of the application.
*/
public PathView(Context context) {
this(context, null);
}
/**
* Default constructor.
*
* @param context The Context of the application.
* @param attrs attributes provided from the resources.
*/
public PathView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
/**
* Default constructor.
*
* @param context The Context of the application.
* @param attrs attributes provided from the resources.
* @param defStyle Default style.
*/
public PathView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
paint.setStyle(Paint.Style.STROKE);
getFromAttributes(context, attrs);
}查看自己定义属性的xml，里面共三个自己定义属性，pathColor为路径颜色，默认值为绿色0xff00ff00，pathWidth为路径宽度，默认值为8.0f，svg为路径文件
" data-snippet-id="ext.8372b925ab36c18fbcb3da24aa7ee54f" data-snippet-saved="false" data-codota-status="done"><?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="PathView">
<attr name="pathColor" format="color"/>
<attr name="pathWidth" format="float"/>
<attr name="svg" format="reference"/>
</declare-styleable>
</resources>
通过getFromAttributes函数获得这些自定属性，并赋值给成员变量，最后通过finally块回收资源
/**
* Get all the fields from the attributes .
*
* @param context The Context of the application.
* @param attrs attributes provided from the resources.
*/
private void getFromAttributes(Context context, AttributeSet attrs) {
final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.PathView);
try {
if (a != null) {
paint.setColor(a.getColor(R.styleable.PathView_pathColor, 0xff00ff00));
paint.setStrokeWidth(a.getFloat(R.styleable.PathView_pathWidth, 8.0f));
svgResourceId = a.getResourceId(R.styleable.PathView_svg, 0);
}
} finally {
if (a != null) {
a.recycle();
}
}
}至于成员变量，这里贴出全部成员变量，详细作用见凝视
paths = new ArrayList(0);
/**
* This is a lock before the view is redrawn
* or resided it must be synchronized with this object.
*/
private final Object mSvgLock = new Object();
/**
* Thread for working with the object above.
*/
private Thread mLoader; /**
* The svg image from the raw directory.
*/
private int svgResourceId;
/**
* Object that build the animation for the path.
*/
private AnimatorBuilder animatorBuilder;
/**
* The progress of the drawing.
*/
private float progress = 0f; /**
* If the used colors are from the svg or from the set color.
*/
private boolean naturalColors;
/**
* If the view is filled with its natural colors after path drawing.
*/
private boolean fillAfter;
/**
* The width of the view.
*/
private int width;
/**
* The height of the view.
*/
private int height;" data-snippet-id="ext.6985d4eda27e815a561fa0bc34510cee" data-snippet-saved="false" data-csrftoken="us74Km0s-ioacrN5aDh_lQUMQoPh1qeiAfqM" data-codota-status="done">/**
* Logging tag.
*/
public static final String LOG_TAG = "PathView";
/**
* The paint for the path.
*/
private Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
/**
* Utils to catch the paths from the svg.
*/
private final SvgUtils svgUtils = new SvgUtils(paint);
/**
* All the paths provided to the view. Both from Path and Svg.
*/
private List<SvgUtils.SvgPath> paths = new ArrayList<SvgUtils.SvgPath>(0);
/**
* This is a lock before the view is redrawn
* or resided it must be synchronized with this object.
*/
private final Object mSvgLock = new Object();
/**
* Thread for working with the object above.
*/
private Thread mLoader; /**
* The svg image from the raw directory.
*/
private int svgResourceId;
/**
* Object that build the animation for the path.
*/
private AnimatorBuilder animatorBuilder;
/**
* The progress of the drawing.
*/
private float progress = 0f; /**
* If the used colors are from the svg or from the set color.
*/
private boolean naturalColors;
/**
* If the view is filled with its natural colors after path drawing.
*/
private boolean fillAfter;
/**
* The width of the view.
*/
private int width;
/**
* The height of the view.
*/
private int height;
然后是一些getter和setter方法。
paths) {
for (Path path : paths) {
this.paths.add(new SvgUtils.SvgPath(path, paint));
}
synchronized (mSvgLock) {
updatePathsPhaseLocked();
}
}
/**
* Set path to be drawn and animated.
*
* @param path - Paths that can be drawn.
*/
public void setPath(final Path path) {
paths.add(new SvgUtils.SvgPath(path, paint));
synchronized (mSvgLock) {
updatePathsPhaseLocked();
}
}
/**
* If the real svg need to be drawn after the path animation.
*
* @param fillAfter - boolean if the view needs to be filled after path animation.
*/
public void setFillAfter(final boolean fillAfter) {
this.fillAfter = fillAfter;
}
/**
* Animator for the paths of the view.
*
* @return The AnimatorBuilder to build the animation.
*/
public AnimatorBuilder getPathAnimator() {
if (animatorBuilder == null) {
animatorBuilder = new AnimatorBuilder(this);
}
return animatorBuilder;
}
/**
* Get the path color.
*
* @return The color of the paint.
*/
public int getPathColor() {
return paint.getColor();
}
/**
* Set the path color.
*
* @param color -The color to set to the paint.
*/
public void setPathColor(final int color) {
paint.setColor(color);
}
/**
* Get the path width.
*
* @return The width of the paint.
*/
public float getPathWidth() {
return paint.getStrokeWidth();
}
/**
* Set the path width.
*
* @param width - The width of the path.
*/
public void setPathWidth(final float width) {
paint.setStrokeWidth(width);
}
/**
* Get the svg resource id.
*
* @return The svg raw resource id.
*/
public int getSvgResource() {
return svgResourceId;
}
/**
* Set the svg resource id.
*
* @param svgResource - The resource id of the raw svg.
*/
public void setSvgResource(int svgResource) {
svgResourceId = svgResource;
}
/**
* If the real svg need to be drawn after the path animation.
*
* @param fillAfter - boolean if the view needs to be filled after path animation.
*/
public void setFillAfter(final boolean fillAfter) {
this.fillAfter = fillAfter;
}
/**
* Animate this property. It is the percentage of the path that is drawn.
* It must be [0,1].
*
* @param percentage float the percentage of the path.
*/
public void setPercentage(float percentage) {
if (percentage 1.0f) {
throw new IllegalArgumentException("setPercentage not between 0.0f and 1.0f");
}
progress = percentage;
synchronized (mSvgLock) {
updatePathsPhaseLocked();
}
invalidate();
}" data-snippet-id="ext.1be3027e509316e9e2378a76aa3aa94e" data-snippet-saved="false" data-csrftoken="SeP2anif-STH2gPOCQWUpbGDdCh2FrxssGrM" data-codota-status="done"> /**
* Set paths to be drawn and animated.
*
* @param paths - Paths that can be drawn.
*/
public void setPaths(final List<Path> paths) {
for (Path path : paths) {
this.paths.add(new SvgUtils.SvgPath(path, paint));
}
synchronized (mSvgLock) {
updatePathsPhaseLocked();
}
}
/**
* Set path to be drawn and animated.
*
* @param path - Paths that can be drawn.
*/
public void setPath(final Path path) {
paths.add(new SvgUtils.SvgPath(path, paint));
synchronized (mSvgLock) {
updatePathsPhaseLocked();
}
}
/**
* If the real svg need to be drawn after the path animation.
*
* @param fillAfter - boolean if the view needs to be filled after path animation.
*/
public void setFillAfter(final boolean fillAfter) {
this.fillAfter = fillAfter;
}
/**
* Animator for the paths of the view.
*
* @return The AnimatorBuilder to build the animation.
*/
public AnimatorBuilder getPathAnimator() {
if (animatorBuilder == null) {
animatorBuilder = new AnimatorBuilder(this);
}
return animatorBuilder;
}
/**
* Get the path color.
*
* @return The color of the paint.
*/
public int getPathColor() {
return paint.getColor();
}
/**
* Set the path color.
*
* @param color -The color to set to the paint.
*/
public void setPathColor(final int color) {
paint.setColor(color);
}
/**
* Get the path width.
*
* @return The width of the paint.
*/
public float getPathWidth() {
return paint.getStrokeWidth();
}
/**
* Set the path width.
*
* @param width - The width of the path.
*/
public void setPathWidth(final float width) {
paint.setStrokeWidth(width);
}
/**
* Get the svg resource id.
*
* @return The svg raw resource id.
*/
public int getSvgResource() {
return svgResourceId;
}
/**
* Set the svg resource id.
*
* @param svgResource - The resource id of the raw svg.
*/
public void setSvgResource(int svgResource) {
svgResourceId = svgResource;
}
/**
* If the real svg need to be drawn after the path animation.
*
* @param fillAfter - boolean if the view needs to be filled after path animation.
*/
public void setFillAfter(final boolean fillAfter) {
this.fillAfter = fillAfter;
}
/**
* Animate this property. It is the percentage of the path that is drawn.
* It must be [0,1].
*
* @param percentage float the percentage of the path.
*/
public void setPercentage(float percentage) {
if (percentage < 0.0f || percentage > 1.0f) {
throw new IllegalArgumentException("setPercentage not between 0.0f and 1.0f");
}
progress = percentage;
synchronized (mSvgLock) {
updatePathsPhaseLocked();
}
invalidate();
}
然后通过一个函数进行路径的更新
/**
* This refreshes the paths before draw and resize.
*/
private void updatePathsPhaseLocked() {
final int count = paths.size();
for (int i = 0; i < count; i++) {
SvgUtils.SvgPath svgPath = paths.get(i);
svgPath.path.reset();
svgPath.measure.getSegment(0.0f, svgPath.length * progress, svgPath.path, true);
// Required only for Android 4.4 and earlier
svgPath.path.rLineTo(0.0f, 0.0f);
}
}接着就一大堆measure啊，draw啊
@Override
protected void onSizeChanged(final int w, final int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
if (mLoader != null) {
try {
mLoader.join();
} catch (InterruptedException e) {
Log.e(LOG_TAG, "Unexpected error", e);
}
}
if (svgResourceId != 0) {
mLoader = new Thread(new Runnable() {
@Override
public void run() {
svgUtils.load(getContext(), svgResourceId);
synchronized (mSvgLock) {
width = w - getPaddingLeft() - getPaddingRight();
height = h - getPaddingTop() - getPaddingBottom();
paths = svgUtils.getPathsForViewport(width, height);
updatePathsPhaseLocked();
}
}
}, "SVG Loader");
mLoader.start();
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (svgResourceId != 0) {
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
setMeasuredDimension(widthSize, heightSize);
return;
}
int desiredWidth = 0;
int desiredHeight = 0;
final float strokeWidth = paint.getStrokeWidth() / 2;
for (SvgUtils.SvgPath path : paths) {
desiredWidth += path.bounds.left + path.bounds.width() + strokeWidth;
desiredHeight += path.bounds.top + path.bounds.height() + strokeWidth;
}
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(widthMeasureSpec);
int measuredWidth, measuredHeight;
if (widthMode == MeasureSpec.AT_MOST) {
measuredWidth = desiredWidth;
} else {
measuredWidth = widthSize;
}
if (heightMode == MeasureSpec.AT_MOST) {
measuredHeight = desiredHeight;
} else {
measuredHeight = heightSize;
}
setMeasuredDimension(measuredWidth, measuredHeight);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
synchronized (mSvgLock) {
canvas.save();
canvas.translate(getPaddingLeft(), getPaddingTop());
final int count = paths.size();
for (int i = 0; i < count; i++) {
final SvgUtils.SvgPath svgPath = paths.get(i);
final Path path = svgPath.path;
final Paint paint1 = naturalColors ? svgPath.paint : paint;
canvas.drawPath(path, paint1);
}
fillAfter(canvas);
canvas.restore();
}
}
/**
* If there is svg , the user called setFillAfter(true) and the progress is finished.
*
* @param canvas Draw to this canvas.
*/
private void fillAfter(final Canvas canvas) {
if (svgResourceId != 0 && fillAfter && progress == 1f) {
svgUtils.drawSvgAfter(canvas, width, height);
}
}我们看到他重写了onSizeChanged方法。首先推断线程是否是null，假设不为null，则调用join方法,让该thread运行完run方法里面的东西后。再运行join()方法后面的代码。
后面的代码就是起了一个线程获取宽度，高度。路径并更新路径等信息。
onMeasure()方法里就是一些測量内容了。详细測量逻辑见源代码。
onDraw()方法主要完毕绘制，事实上非常easy，就是在Canvas上绘图。遍历全部Path，画在画布上，画完后调用了fillAfter方法，假设设置了svg资源，以及fillAfter 成员变量为true。动画已完毕，则会保持动画
最后这个自己定义View类里使用了创建者模式进行创建路径动画，比方动画的时间，插值器。延时，监听器等等。
/**
* Object for building the animation of the path of this view.
*/
public static class AnimatorBuilder {
/**
* Duration of the animation.
*/
private int duration = 350;
/**
* Interpolator for the time of the animation.
*/
private Interpolator interpolator;
/**
* The delay before the animation.
*/
private int delay = 0;
/**
* ObjectAnimator that constructs the animation.
*/
private final ObjectAnimator anim;
/**
* Listener called before the animation.
*/
private ListenerStart listenerStart;
/**
* Listener after the animation.
*/
private ListenerEnd animationEnd;
/**
* Animation listener.
*/
private PathViewAnimatorListener pathViewAnimatorListener;
/**
* Default constructor.
*
* @param pathView The view that must be animated.
*/
public AnimatorBuilder(final PathView pathView) {
anim = ObjectAnimator.ofFloat(pathView, "percentage", 0.0f, 1.0f);
}
/**
* Set the duration of the animation.
*
* @param duration - The duration of the animation.
* @return AnimatorBuilder.
*/
public AnimatorBuilder duration(final int duration) {
this.duration = duration;
return this;
}
/**
* Set the Interpolator.
*
* @param interpolator - Interpolator.
* @return AnimatorBuilder.
*/
public AnimatorBuilder interpolator(final Interpolator interpolator) {
this.interpolator = interpolator;
return this;
}
/**
* The delay before the animation.
*
* @param delay - int the delay
* @return AnimatorBuilder.
*/
public AnimatorBuilder delay(final int delay) {
this.delay = delay;
return this;
}
/**
* Set a listener before the start of the animation.
*
* @param listenerStart an interface called before the animation
* @return AnimatorBuilder.
*/
public AnimatorBuilder listenerStart(final ListenerStart listenerStart) {
this.listenerStart = listenerStart;
if (pathViewAnimatorListener == null) {
pathViewAnimatorListener = new PathViewAnimatorListener();
anim.addListener(pathViewAnimatorListener);
}
return this;
}
/**
* Set a listener after of the animation.
*
* @param animationEnd an interface called after the animation
* @return AnimatorBuilder.
*/
public AnimatorBuilder listenerEnd(final ListenerEnd animationEnd) {
this.animationEnd = animationEnd;
if (pathViewAnimatorListener == null) {
pathViewAnimatorListener = new PathViewAnimatorListener();
anim.addListener(pathViewAnimatorListener);
}
return this;
}
/**
* Starts the animation.
*/
public void start() {
anim.setDuration(duration);
anim.setInterpolator(interpolator);
anim.setStartDelay(delay);
anim.start();
}
/**
* Animation listener to be able to provide callbacks for the caller.
*/
private class PathViewAnimatorListener implements Animator.AnimatorListener {
@Override
public void onAnimationStart(Animator animation) {
if (listenerStart != null) listenerStart.onAnimationStart();
}
@Override
public void onAnimationEnd(Animator animation) {
if (animationEnd != null) animationEnd.onAnimationEnd();
}
@Override
public void onAnimationCancel(Animator animation) {
}
@Override
public void onAnimationRepeat(Animator animation) {
}
}
/**
* Called when the animation start.
*/
public interface ListenerStart {
/**
* Called when the path animation start.
*/
void onAnimationStart();
}
/**
* Called when the animation end.
*/
public interface ListenerEnd {
/**
* Called when the path animation end.
*/
void onAnimationEnd();
}
}SVG文件的载入等工作都在SvgUtils类中完毕。
依赖了一个jar包，该工具类主要负责资源文件的载入和初始化
构造方法是传入一个画笔
/**
* Init the SVGUtils with a paint for coloring.
*
* @param sourcePaint - the paint for the coloring.
*/
public SvgUtils(final Paint sourcePaint) {
mSourcePaint = sourcePaint;
} 资源文件的载入
/**
* Loading the svg from the resources.
*
* @param context Context object to get the resources.
* @param svgResource int resource id of the svg.
*/
public void load(Context context, int svgResource) {
if (mSvg != null) return;
try {
mSvg = SVG.getFromResource(context, svgResource);
mSvg.setDocumentPreserveAspectRatio(PreserveAspectRatio.UNSCALED);
} catch (SVGParseException e) {
Log.e(LOG_TAG, "Could not load specified SVG resource", e);
}
} 其余的方法就是跟绘制有关了。
有兴趣自己去下源代码看看。这里不做展开了。
源代码解析完毕后，我们使用一下这个库。我们首先使用github上的svg文件做測试。
在布局文件中加入代码
<com.eftimoff.androipathview.PathView
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/pathView"
android:layout_width="150dp"
android:layout_height="150dp"
app:svg="@raw/monitor"
app:pathWidth="2"
app:pathColor="#ff0000"
/>
然后就能够通过getPathAnimator方法获得创建者对象，通过一系列的链式调用配置动画，比方延时，动画持续时间。插值器，监听器，最后调用start開始动画。
PathView mPathView= (PathView) findViewById(R.id.pathView);
mPathView.getPathAnimator()
.delay(1000)
.duration(3000)
.interpolator(new BounceInterpolator())
.listenerStart(new PathView.AnimatorBuilder.ListenerStart() {
@Override
public void onAnimationStart() {
Log.e("TAG", "start");
}
})
.listenerEnd(new PathView.AnimatorBuilder.ListenerEnd() {
@Override
public void onAnimationEnd() {
Log.e("TAG","end");
}
}).start();
终于效果就是这样子
当然我们也能够使用svg文件中的颜色，让它绘制完毕后绘制终于真正的svg，能够加入下面代码
mPathView.useNaturalColors();
mPathView.setFillAfter(true);终于效果例如以下 
当然你可能想让它停留在某个状态点，你能够使用下面函数进行设置，參数值范围为0到1
mPathView.setPercentage(0.8f);甚至你能够不用svg文件，你能够使用Path类
Path path=new Path();
path.moveTo(0.0f, 0.0f);
path.lineTo(length / 4f, 0.0f);
path.lineTo(length, height / 2.0f);
path.lineTo(length / 4f, height);
path.lineTo(0.0f, height);
path.lineTo(length * 3f / 4f, height / 2f);
path.lineTo(0.0f, 0.0f);
path.close();
mPathView.setPath(path);还有List类型
paths = new ArrayList();
//to do paths.add(path)
mPathView.setPaths(paths);" data-snippet-id="ext.bbf20c1365e0d132851cfceab79afdd5" data-snippet-saved="false" data-csrftoken="4Ep2pzXU-TCk-4L9GymtrqhT8iG_nnud_1Do" data-codota-status="done">List<Path> paths = new ArrayList<Path>();
//to do paths.add(path)
mPathView.setPaths(paths);
当然对于自己定义属性，也能够通过代码设置
mPathView.setPathColor(0x00ff00);
mPathView.setPathWidth(5f);
mPathView.setSvgResource(R.raw.logout);最后贴一下svg的一些命令，每一个命令都有大写和小写形式，大写代表后面的參数是绝对坐标，小写表示相对坐标。參数之间用空格或逗号隔开
- M： move to 移动绘制点
- L：line to 直线
- Z：close 闭合
- C：cubic bezier 三次贝塞尔曲线
- Q：quatratic bezier 二次贝塞尔曲线
- A：ellipse 圆弧
详细解释
- M (x y) 移动到x,y
- L (x y) 直线连到x,y，还有简化命令H(x) 水平连接、V(y)垂直连接
- Z。没有參数。连接起点和终点
- C(x1 y1 x2 y2 x y)，控制点x1,y1 x2,y2，终点x,y
- Q(x1 y1 x y)，控制点x1,y1，终点x,y
- A(rx ry x-axis-rotation large-arc-flag sweep-flag x y)
rx ry 椭圆半径
x-axis-rotation x轴旋转角度
large-arc-flag 为0时表示取小弧度。1时取大弧度
sweep-flag 0取逆时针方向，1取顺时针方向
很多其它详情请參考w3c