android进阶-Android控件架构与自定义控件详解（二）

1.重新View绘制新的控件

public class CircleProgressView extends View {

private int mMeasureHeigth;
private int mMeasureWidth;

private Paint mCirclePaint;
private float mCircleXY;
private float mRadius;

private Paint mArcPaint;
private RectF mArcRectF;
private float mSweepAngle;
private float mSweepValue = 66;

private Paint mTextPaint;
private String mShowText;
private float mShowTextSize;

public CircleProgressView(Context context, AttributeSet attrs,
int defStyleAttr) {
super(context, attrs, defStyleAttr);
}

public CircleProgressView(Context context, AttributeSet attrs) {
super(context, attrs);
}

public CircleProgressView(Context context) {
super(context);
}

@Override
protected void onMeasure(int widthMeasureSpec,
int heightMeasureSpec) {
mMeasureWidth = MeasureSpec.getSize(widthMeasureSpec);
mMeasureHeigth = MeasureSpec.getSize(heightMeasureSpec);
setMeasuredDimension(mMeasureWidth, mMeasureHeigth);
initView();
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// 绘制圆
canvas.drawCircle(mCircleXY, mCircleXY, mRadius, mCirclePaint);
// 绘制弧线
canvas.drawArc(mArcRectF, 270, mSweepAngle, false, mArcPaint);
// 绘制文字
canvas.drawText(mShowText, 0, mShowText.length(),
mCircleXY, mCircleXY + (mShowTextSize / 4), mTextPaint);
}

private void initView() {
float length = 0;
if (mMeasureHeigth >= mMeasureWidth) {
length = mMeasureWidth;
} else {
length = mMeasureHeigth;
}

//圆
mCircleXY = length / 2;
mRadius = (float) (length * 0.5 / 2);
mCirclePaint = new Paint();
mCirclePaint.setAntiAlias(true);
mCirclePaint.setColor(getResources().getColor(
android.R.color.holo_blue_bright));
//弧线
mArcRectF = new RectF(
(float) (length * 0.1),
(float) (length * 0.1),
(float) (length * 0.9),
(float) (length * 0.9));
mSweepAngle = (mSweepValue / 100f) * 360f;
mArcPaint = new Paint();
mArcPaint.setAntiAlias(true);
mArcPaint.setColor(getResources().getColor(
android.R.color.holo_blue_bright));
mArcPaint.setStrokeWidth((float) (length * 0.1));
mArcPaint.setStyle(Style.STROKE);

mShowText = setShowText();
mShowTextSize = setShowTextSize();
mTextPaint = new Paint();
mTextPaint.setTextSize(mShowTextSize);
mTextPaint.setTextAlign(Paint.Align.CENTER);
}

private float setShowTextSize() {
this.invalidate();
return 50;
}

private String setShowText() {
this.invalidate();
return "Android Skill";
}

public void forceInvalidate() {
this.invalidate();
}

//设置不同状态值
public void setSweepValue(float sweepValue) {
if (sweepValue != 0) {
mSweepValue = sweepValue;
} else {
mSweepValue = 25;
}
this.invalidate();
}
}

demo下载地址

public class VolumeView extends View {

private int mWidth;
private int mRectWidth;
private int mRectHeight;
private Paint mPaint;
private int mRectCount;
private int offset = 5;
private double mRandom;
private LinearGradient mLinearGradient;

public VolumeView(Context context) {
super(context);
initView();
}

public VolumeView(Context context, AttributeSet attrs) {
super(context, attrs);
initView();
}

public VolumeView(Context context, AttributeSet attrs,
int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView();
}

private void initView() {
mPaint = new Paint();
mPaint.setColor(Color.BLUE);
mPaint.setStyle(Paint.Style.FILL);
mRectCount = 12;
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mWidth = getWidth();
mRectHeight = getHeight();
mRectWidth = (int) (mWidth * 0.6 / mRectCount);
mLinearGradient = new LinearGradient(
0,
0,
mRectWidth,
mRectHeight,
Color.YELLOW,
Color.BLUE,
Shader.TileMode.CLAMP);
mPaint.setShader(mLinearGradient);
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
for (int i = 0; i < mRectCount; i++) {
mRandom = Math.random();
float currentHeight = (float) (mRectHeight * mRandom);
canvas.drawRect(
(float) (mWidth * 0.4 / 2 + mRectWidth * i + offset),
currentHeight,
(float) (mWidth * 0.4 / 2 + mRectWidth * (i + 1)),
mRectHeight,
mPaint);
}
postInvalidateDelayed(300);
}
}

2.自定义ViewGroup

demo下载地址

public class MyScrollView extends ViewGroup {

private int mScreenHeight;
private Scroller mScroller;
private int mLastY;
private int mStart;
private int mEnd;

public MyScrollView(Context context) {
super(context);
initView(context);
}

public MyScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
initView(context);
}

public MyScrollView(Context context, AttributeSet attrs,
int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView(context);
}

private void initView(Context context) {
WindowManager wm = (WindowManager) context.getSystemService(
Context.WINDOW_SERVICE);
DisplayMetrics dm = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(dm);
mScreenHeight = dm.heightPixels;
mScroller = new Scroller(context);
}

/**
* 确定整个ViewGroup的高度，即子view进行放置位置的设定
* 每一个View占一屏的高度，因此整个ViewGroup的高度寄子VIEW的个数乘以屏幕的高度
* @param changed
* @param l
* @param t
* @param r
* @param b
*/
@Override
protected void onLayout(boolean changed,
int l, int t, int r, int b) {
int childCount = getChildCount();
// 设置ViewGroup的高度
MarginLayoutParams mlp = (MarginLayoutParams) getLayoutParams();
mlp.height = mScreenHeight * childCount;
setLayoutParams(mlp);
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != View.GONE) {
child.layout(l, i * mScreenHeight,
r, (i + 1) * mScreenHeight);
}
}
}

/**
* 在ViewGroup能够滚动之前，需要先放置好它的子view
* 使用遍历的方式来通知子View对自身进行测量
* @param widthMeasureSpec
* @param heightMeasureSpec
*/
@Override
protected void onMeasure(int widthMeasureSpec,
int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int count = getChildCount();
for (int i = 0; i < count; ++i) {
View childView = getChildAt(i);
measureChild(childView,
widthMeasureSpec, heightMeasureSpec);
}
}

/**
* 给viewGroup添加响应事件
* 在onTouchEvent()的ACTION_MOVE事件中，只要使用scrollBy(0,dy)
* @param event
* @return
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
int y = (int) event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mLastY = y;
mStart = getScrollY();
break;
case MotionEvent.ACTION_MOVE:
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
int dy = mLastY - y;
if (getScrollY() < 0) {
dy = 0;
}
if (getScrollY() > getHeight() - mScreenHeight) {
dy = 0;
}
scrollBy(0, dy);
mLastY = y;
break;
case MotionEvent.ACTION_UP:
int dScrollY = checkAlignment();
if (dScrollY > 0) {
if (dScrollY < mScreenHeight / 3) {
mScroller.startScroll(
0, getScrollY(),
0, -dScrollY);
} else {
mScroller.startScroll(
0, getScrollY(),
0, mScreenHeight - dScrollY);
}
} else {
if (-dScrollY < mScreenHeight / 3) {
mScroller.startScroll(
0, getScrollY(),
0, -dScrollY);
} else {
mScroller.startScroll(
0, getScrollY(),
0, -mScreenHeight - dScrollY);
}
}
break;
}
postInvalidate();
return true;
}
private int checkAlignment() {
int mEnd = getScrollY();
boolean isUp = ((mEnd - mStart) > 0) ? true : false;
int lastPrev = mEnd % mScreenHeight;
int lastNext = mScreenHeight - lastPrev;
if (isUp) {
//向上的
return lastPrev;
} else {
return -lastNext;
}
}
@Override
public void computeScroll() {
super.computeScroll();
if (mScroller.computeScrollOffset()) {
scrollTo(0, mScroller.getCurrY());
postInvalidate();
}
}
}