1、效果展示
file_chartview.gif
2、核心代码
- ScrollChartView 可滚动的自定义图表
每次滚动完成 计算滚动的位置，使indicate居中并回调当前位置的position 供外部使用
/**
* 调整indicate，使其居中。
*/
private void adjustIndicate() {
if (!mOverScroller.isFinished()) {
mOverScroller.abortAnimation();
}
int position = computeSelectedPosition();
int scrollX = getScrollByPosition(position);
scrollX -= getScrollX();
this.position = position;
if (scrollX != 0) {
mOverScroller.startScroll(getScrollX(), getScrollY(), scrollX, 0);
invalidateView();
}
//滚动完毕回调
onScaleChanged(position);
}
根据传入的position 计算出每个indicate的位置，用于画图
例如position = 5 * indicate总宽度(indicate宽度+indicatePadding间隔*2) = 80
则该下标的位置为 left = 400 , right = left+indicate。
/**
* 计算indicate的位置
*/
private void computeIndicateLoc(Rect outRect, int position) {
if (outRect == null) {
return;
}
int height = getHeight();
int indicate = getIndicateWidth();
int left = (indicate * position);
int right = left + indicate;
int top = getPaddingTop();
int bottom = height - getPaddingBottom();
if (isAlignTop()) {
bottom -= mIndicateBottomPadding;
} else {
top += mIndicateBottomPadding;
}
outRect.set(left, top, right, bottom);
}
上面两个方法是调整indicate 并计算出他的位置，得到这些参数后，就可以开始画图了
/**
* 绘制网格线
*/
private void drawGridLine(Canvas canvas) {
for (int i = 0; i < mList.size(); i++) {
computeIndicateLoc(mIndicateLoc, i);
int left = mIndicateLoc.left + mIndicatePadding;
int right = mIndicateLoc.right - mIndicatePadding;
int bottom = getHeight() - mShadowMarginHeight;
canvas.drawRect(left, 0, right, bottom, mGridPaint);
}
}
this.position == position 判断当前的position与将要绘制的position是否一致
是则改变其颜色并判断SDK版本是否大于21(支持画圆角的矩形)
/**
* 绘制指示标
*/
private void drawIndicate(Canvas canvas, int position) {
computeIndicateLoc(mIndicateLoc, position);
int left = mIndicateLoc.left + mIndicatePadding;
int right = mIndicateLoc.right - mIndicatePadding;
int bottom = mIndicateLoc.bottom;
int top = bottom - mIndicateHeight;
if (this.position == position) {
mIndicatePaint.setColor(mSelectedColor);
} else {
mIndicatePaint.setColor(mIndicateColor);
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
canvas.drawRoundRect(left, top, right, bottom, 5, 5, mIndicatePaint);
} else {
canvas.drawRect(left, top, right, bottom, mIndicatePaint);
}
}
同上，如果position一致则改变其大小和颜色
/**
* 绘制文字
*/
private void drawText(Canvas canvas, int position, String text) {
computeIndicateLoc(mIndicateLoc, position);
if (this.position == position) {
mTextPaint.setTextSize(mTextSelectedSize);
mTextPaint.setColor(mSelectedColor);
} else {
mTextPaint.setTextSize(mTextSize);
mTextPaint.setColor(mTextColor);
}
int x = (mIndicateLoc.left + mIndicateLoc.right) / 2;
int y = mIndicateLoc.bottom + mIndicateBottomPadding - mTextBottomPadding;
if (!isAlignTop()) {
y = mIndicateLoc.top;
mTextPaint.getTextBounds(text, 0, text.length(), mIndicateLoc);
//增加一些偏移
y += mIndicateLoc.top / 2;
}
canvas.drawText(text, x, y, mTextPaint);
}
绘制Line,支持折线和曲线，后续还会支持柱状图，曲线的绘制方式可以去了解下贝塞尔曲线。
/**
* 绘制折线图
*/
private void drawLine(Canvas canvas) {
Path path = new Path();
path.moveTo(mList.get(0).x, mList.get(0).y);
for (int i = 1; i < mList.size(); i++) {
path.lineTo(mList.get(i).x, mList.get(i).y);
}
canvas.drawPath(path, mLinePaint);
}
/**
* 绘制曲线图
*/
private void drawScrollLine(Canvas canvas) {
Point pStart;
Point pEnd;
Path path = new Path();
for (int i = 0; i < mList.size() - 1; i++) {
pStart = mList.get(i);
pEnd = mList.get(i + 1);
Point point3 = new Point();
Point point4 = new Point();
float wd = (pStart.x + pEnd.x) / 2;
point3.x = wd;
point3.y = pStart.y;
point4.x = wd;
point4.y = pEnd.y;
path.moveTo(pStart.x, pStart.y);
path.cubicTo(point3.x, point3.y, point4.x, point4.y, pEnd.x, pEnd.y);
canvas.drawPath(path, mLinePaint);
}
}
最后是绘制阴影，判断是折线还是曲线， 绘制阴影的方式跟绘制Line的方式差不多
重点是path.close() 如果连接Path起点和终点能形成一个闭合图形
则会将起点和终点连接起来形成一个闭合图形
/**
* 绘制阴影
*/
private void drawShadow(Canvas canvas) {
if (mLineType == LineType.ARC) {
Point pStart;
Point pEnd;
Path path = new Path();
for (int i = 0; i < mList.size() - 1; i++) {
pStart = mList.get(i);
pEnd = mList.get(i + 1);
Point point3 = new Point();
Point point4 = new Point();
float wd = (pStart.x + pEnd.x) / 2;
point3.x = wd;
point3.y = pStart.y;
point4.x = wd;
point4.y = pEnd.y;
path.moveTo(pStart.x, pStart.y);
path.cubicTo(point3.x, point3.y, point4.x, point4.y, pEnd.x, pEnd.y);
//减去文字和指示标的高度
path.lineTo(pEnd.x, getHeight() - mShadowMarginHeight);
path.lineTo(pStart.x, getHeight() - mShadowMarginHeight);
}
path.close();
canvas.drawPath(path, mShadowPaint);
} else {
Path path = new Path();
path.moveTo(mList.get(0).x, mList.get(0).y);
for (int i = 1; i < mList.size(); i++) {
path.lineTo(mList.get(i).x, mList.get(i).y);
}
//链接最后两个点
int index = mList.size() - 1;
path.lineTo(mList.get(index).x, getHeight() - mShadowMarginHeight);
path.lineTo(mList.get(0).x, getHeight() - mShadowMarginHeight);
path.close();
canvas.drawPath(path, mShadowPaint);
}
}
- CircleIndicatorView 圆形的指示器
这个自定义控件就比较简单，总共就三个重要的方法
1、画圆 2、画线 3、设置圆的Y坐标
private void drawCircle(Canvas canvas) {
mCirclePaint.setColor(mCircleColor);
canvas.drawCircle(getWidth() / 2, mCircleY, mCircleRadius, mCirclePaint);
mCirclePaint.setColor(mCircleBackColor);
canvas.drawCircle(getWidth() / 2, mCircleY, mCircleRadius / 2, mCirclePaint);
}
private void drawLine(Canvas canvas) {
int left = getWidth() / 2;
int bottom = getHeight();
int top = 0;
Path path = new Path();
path.moveTo(left, top);
path.lineTo(left, bottom);
canvas.drawPath(path, mLinePaint);
}
public void setCircleY(float circleY) {
mCircleY = circleY;
invalidate();
}
结合之前的图表控件回调，获取到position 然后根据position获取到当前下标的坐标，赋值Y轴值给圆形控件
scrollChartView.setOnScaleListener(new ScrollChartView.OnScaleListener() {
@Override
public void onScaleChanged(int position) {
ScrollChartView.Point point = scrollChartView.getList().get(position);
circleIndicatorView.setCircleY(point.y);
}
});
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