实现的效果我一会贴上，我先说下原理，我们知道要实现在canvas上画线，不就是要搞一个paint嘛，然后首先肯定要设置下paint的属性，那么画文字呢，不就是Textpaint吗，
对，就是这么简单，接下来怎么画，折线图主要分为X轴和y轴，x轴表示日期，y表示收益，好，说道这里，大家应该知道怎么去做了，下面直接贴代码，
这个方法是，画x,y坐标系的，以及上面的日期和收益了
private void drawCoordinate(Canvas canvas) {
//坐标系画笔
Paint coordinatePaint = new Paint();
coordinatePaint.setAntiAlias(true);
coordinatePaint.setStrokeWidth(1);
coordinatePaint.setColor(getResources().getColor(R.color.c5));
//坐标系文字画笔
TextPaint coordinateTextPaint = new TextPaint();
coordinateTextPaint.setAntiAlias(true);
coordinateTextPaint.setTextSize(scaleTextSize);
coordinateTextPaint.setAntiAlias(true);
coordinateTextPaint.setColor(scaleTextColor);
coordinateTextPaint.setTextAlign(Align.CENTER);
//水平的刻度线
float verticalScaleStep = getVerticalScaleStep();
coordinateTextPaint.setTextAlign(Align.RIGHT);
float textHeight = getTextHeight(coordinateTextPaint, "8");
for (int i = 0; i < maxVerticalScaleValue; i++) {
float y = getHeight() - bottomPadding - (verticalScaleStep * i);
canvas.drawLine(leftPadding, y, getWidth() - rightPadding, y, coordinatePaint);
canvas.drawText(i + "", leftPadding - 13, y + textHeight / 2, coordinateTextPaint);
}
//垂直的刻度线
float horizontalScaleStep = getHorizontalScaleStep();
for (int i = 0; i < line.getSize(); i++) {
float x = leftPadding + (horizontalScaleStep * i);
if (i == 0) {
canvas.drawLine(x, topPadding, x, getHeight() - bottomPadding, coordinatePaint);
}
coordinateTextPaint.setColor(mTouchIndex == i ? verticalLineColor : scaleTextColor);
coordinateTextPaint.setTextAlign(i == 0 ? Align.LEFT : Align.CENTER);
canvas.drawText(line.getPoint(i).getX(), x, getHeight() - bottomPadding + textHeight + 10, coordinateTextPaint);
}
}
但是产品有个需求啊，就是点击当前日期可以查看我的收益，并且在交汇点上展示出来
private void drawCurve(Canvas canvas) {
Paint curvePaint = new Paint();//曲线画笔
curvePaint.setColor(curveColor);
curvePaint.setAntiAlias(true);
curvePaint.setStrokeWidth(curveStrokeWidth);
float horizontalScaleStep = getHorizontalScaleStep();
float lastXPixels = 0, newYPixels = 0;
float lastYPixels = 0, newXPixels = 0;
float useHeight = getHeight() - bottomPadding - topPadding;
for (int i = 0; i < line.getSize(); i++) {
float yPercent = line.getPoint(i).getY() / maxVerticalScaleValue;
if (i == 0) {
lastXPixels = leftPadding + i * horizontalScaleStep;
lastYPixels = getHeight() - bottomPadding - useHeight * yPercent;
} else {
newXPixels = leftPadding + i * horizontalScaleStep;
newYPixels = getHeight() - bottomPadding - useHeight * yPercent;
canvas.drawLine(lastXPixels, lastYPixels, newXPixels, newYPixels, curvePaint);
lastXPixels = newXPixels;
lastYPixels = newYPixels;
}
line.getPoint(i).fLineX = lastXPixels;
line.getPoint(i).fLineY = lastYPixels;
}
}
点击交汇点，有文字提示说明，
private void drawTipRect(Canvas canvas) {
if (mTouchIndex == -1) return;
LinePoint point = line.getPoint(mTouchIndex);
float x = point.fLineX;
float y = point.fLineY;
// 描绘竖线
Paint paint = new TextPaint();
PathEffect effects = new DashPathEffect(new float[]{5, 5, 5, 5}, 1);
paint.setPathEffect(effects);
paint.setAntiAlias(true);
paint.setStrokeWidth(verticalLineStrokeWidth);
paint.setColor(verticalLineColor);
canvas.drawLine(x, topPadding, x, getHeight() - bottomPadding, paint);
//描绘交汇圆点
paint.setPathEffect(null);
paint.setStyle(Paint.Style.FILL_AND_STROKE);
paint.setColor(Color.WHITE);
canvas.drawCircle(x, y, circleRadius, paint);
paint.setStyle(Paint.Style.STROKE);
paint.setColor(circleColor);
paint.setStrokeWidth(circleStrokeWidth);
canvas.drawCircle(x, y, circleRadius, paint);
float midY = (topPadding + getHeight() - bottomPadding) / 2;
float midX = (leftPadding + getWidth() - rightPadding) / 2;
//描绘圆角矩形
TextPaint textPaint = new TextPaint();
textPaint.setTextSize(tipTextSize);
textPaint.setTextAlign(Align.CENTER);
textPaint.setColor(tipTextColor);
textPaint.setAntiAlias(true);
String label = tipPrefix + point.getY();
float textWidth = textPaint.measureText(label) + 15;
float textHeight = getTextHeight(textPaint, label) + 8;
float hMargin = 10;//水平间距
float vMargin = 8;//垂直间距
float w = textWidth + hMargin * 2;//宽
float h = textHeight + vMargin * 2;//高
RectF rect = new RectF();
if (x > midX) {
rect.right = x - hMargin;
rect.left = x - w;
} else {
rect.left = x + hMargin;
rect.right = x + w;
}
if (y > midY) {
rect.top = y - h;
rect.bottom = y - vMargin;
} else {
rect.bottom = y + h;
rect.top = y + vMargin;
}
Paint roundRectPaint = new Paint();
roundRectPaint.setColor(tipRectColor);
roundRectPaint.setStyle(Paint.Style.FILL);
roundRectPaint.setAntiAlias(true);
canvas.drawRoundRect(rect, 3, 3, roundRectPaint);
// 描绘圆角矩形中间的文字
float roundTextX = (rect.left + rect.right) / 2;
float roundTextY = (rect.top + rect.bottom + getTextHeight(textPaint, label)) / 2;
canvas.drawText(label, roundTextX, roundTextY, textPaint);
}好了核心的代码就这么多了，由于我们把它当做的是控件再用，那么我们在初始化的时候，肯定会引入一些自定义的样式表，
private void initViews(AttributeSet attrs, int defStyle) {
TypedArray typedArray = getContext().obtainStyledAttributes(attrs, R.styleable.LineGraph, defStyle, 0);
scaleTextSize = typedArray.getDimension(R.styleable.LineGraph_scale_text_size, 20);
scaleTextColor = typedArray.getColor(R.styleable.LineGraph_scale_text_color, getResources().getColor(R.color.c5));
tipRectColor = typedArray.getColor(R.styleable.LineGraph_tip_rect_color, getResources().getColor(R.color.c8));
tipTextSize = typedArray.getDimension(R.styleable.LineGraph_tip_text_size, 22);
tipTextColor = typedArray.getColor(R.styleable.LineGraph_tip_text_color, getResources().getColor(R.color.c12));
curveStrokeWidth = typedArray.getDimension(R.styleable.LineGraph_curve_stroke_width, 4);
curveColor = typedArray.getColor(R.styleable.LineGraph_curve_color, getResources().getColor(R.color.c8));
verticalLineStrokeWidth = typedArray.getDimension(R.styleable.LineGraph_vertical_line_stroke_width, 2);
verticalLineColor = typedArray.getColor(R.styleable.LineGraph_vertical_line_color, getResources().getColor(R.color.c8));
circleStrokeWidth = typedArray.getDimensionPixelSize(R.styleable.LineGraph_circle_stroke_width, 3);
circleColor = typedArray.getColor(R.styleable.LineGraph_circle_color, getResources().getColor(R.color.c8));
circleRadius = typedArray.getDimensionPixelSize(R.styleable.LineGraph_circle_radius, 7);
typedArray.recycle();
bottomPadding = dip2px(getContext(), 20);
topPadding = dip2px(getContext(), 10);
leftPadding = dip2px(getContext(), 20);
rightPadding = dip2px(getContext(), 10);
}样式表文件我就不多说了，行如下面的格式，
<declare-styleable name="LineGraph">
<attr name="scale_text_size" format="dimension" />
<attr name="scale_text_color" format="color" />
<attr name="tip_text_size" format="dimension" />
<attr name="tip_text_color" format="color" />
<attr name="tip_rect_color" format="color" />
<attr name="curve_stroke_width" format="dimension" />
<attr name="curve_color" format="color" />
<attr name="vertical_line_stroke_width" format="dimension" />
<attr name="vertical_line_color" format="color" />
<attr name="circle_stroke_width" format="dimension" />
<attr name="circle_color" format="color" />
<attr name="circle_radius" format="dimension" />
</declare-styleable>最后贴上个效果图，有需要的联系我吧，欢迎留言
git下载地址：https://github.com/xiangzhihong/lineview