首先看一下最后实现的效果图
seekbar.png
可左右滑动，点击加减按钮动态改变数值和位置显示。
思路：
1.根据图上UI知道有三种状态
实现：
首先我们自定义一个类MySeekBar继承View。并实现最重要的onDraw，onMeasure方法。
1.首先定义一个样式，用来以后设置底部颜色，滑中颜色，字体大小，颜色等
资源样式
2.实现MySeekBar构造器。初始化资源，与需要的画笔。（注意获得资源后一定要使用recycle()，去进行回收）
public MySeekBar(Context context, AttributeSet attrs) {
super(context, attrs);
TypedArray attr = getTypedArray(context, attrs, R.styleable.MySeekBar);
mTopBarColor = attr.getColor(R.styleable.MySeekBar_mTopBarColor, getResources().getColor(R.color.color_EB7046));//设置滑动时候横条颜色
mBottomBarColor = attr.getColor(R.styleable.MySeekBar_mBottomBarColor, getResources().getColor(R.color.login_font));//默认的横条颜色
month = attr.getBoolean(R.styleable.MySeekBar_month, false);//判断是按年份显示还是月份显示
myText = attr.getString(R.styleable.MySeekBar_mytext);//获得textview显示的后缀
mContext = context;
Data(Calendar.getInstance());//得到当前的日期
windows_width = DisplayMetricsTool.getWidth(mContext);//获得屏幕宽度用来适配各种屏幕
dip_size = DisplayMetricsTool.dip2px(mContext, 75);
//矩形的白色底部画笔
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint = new Paint(); //设置一个笔刷大小是3的黄色的画笔
paint.setStyle(Paint.Style.FILL);//充满
paint.setColor(Color.WHITE);
paint.setAntiAlias(true);// 设置画笔的锯齿效果
//矩形边框的的画笔
whit = new Paint(); //设置一个笔刷大小是3的黄色的画笔
whit.setStyle(Paint.Style.STROKE);
whit.setColor(mTopBarColor);
whit.setStrokeWidth(1);
whit.setAntiAlias(true);// 设置画笔的锯齿效果
//设置字体
textPaint = new Paint();
textPaint.setColor(mTopBarColor);
textPaint.setTextSize(DisplayMetricsTool.canvasTextSize(mContext));
textPaint.setStyle(Paint.Style.FILL);
//该方法即为设置基线上那个点究竟是left,center,还是right 这里我设置为center
textPaint.setTextAlign(Paint.Align.CENTER);
textPaint.setAntiAlias(true);
attr.recycle();
}
3.自定义一个方法设置进度值，默认满进度100.
/**
* 顶部进度条初始百分比进度
*/
private float mOriginalPercent = 0f;
/**
* 设置初始进度值，默认进度最大值为100
*
* @param progress
*/
public void setOriginalProgress(int progress) {
if (month) {//按年显示
progress = 100 - (year - progress);//总进度减去今年和传入年份的差值
} else {
//按月显示
progress = (int) (progress * 8.4);//12月占100的百分比8.4
}
mOriginalPercent = progress / 100f;
if (mOriginalPercent < 0) {
mOriginalPercent = 0.0f;
} else if (mOriginalPercent > 1.0f) {
mOriginalPercent = 1.0f;
}
}
4.需要在onMeasure方法中计算，当前传入的进度换算之后占在屏幕的哪个位置。
//获得密度转像素的大小
private int dip_size;
// view的宽
private int mViewWidth;
// view的高
private int mViewHeight;
// 底部进度条的宽
private int mBottomBarWidth;
//底部进度条左边位置
private int mBottomBarLeft;
// 底部进度条上边位置
private int mBottomBarTop;
// 底部进度条右边位置
private int mBottomBarRight;
// 底部进度条底边位置
private int mBottomBarBottom;
// 顶部进度条的右边位置
private int mTopBarRight;
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if (widthMode == MeasureSpec.AT_MOST) {
mViewWidth = mTvWidth * 4;
} else if (widthMode == MeasureSpec.EXACTLY) {
if (mTvWidth * 4 >= widthSize) {
mViewWidth = mTvWidth * 4;
} else {
mViewWidth = widthSize;
}
}
widthMeasureSpec = MeasureSpec.makeMeasureSpec(mViewWidth, MeasureSpec.EXACTLY);
if (heightMode == MeasureSpec.AT_MOST) {
mViewHeight = mTvHeight + 4 * mPadding;
} else if (heightMode == MeasureSpec.EXACTLY) {
if (heightSize <= mTvHeight + 4 * mPadding) {
mViewHeight = mTvHeight + 4 * mPadding;
} else {
mViewHeight = heightSize;
}
}
heightMeasureSpec = MeasureSpec.makeMeasureSpec(mViewHeight, MeasureSpec.EXACTLY);
mBottomBarWidth = mViewWidth - 2 * mTvWidth - 6 * mPadding;
mBottomBarLeft = mTvWidth + 3 * mPadding;
mBottomBarRight = mViewWidth - mTvWidth - 3 * mPadding;
mBottomBarBottom = (mViewHeight - mTvHeight) / 2 + mTvHeight;
mBottomBarTop = mBottomBarBottom - mBarHeight;
mCircleY = mBottomBarBottom - mBarHeight / 2;//圆心的坐标
mPosition = (int) Math.round((mBottomBarWidth - DisplayMetricsTool.getWidth(mContext) / 6) * mOriginalPercent + 0.5) + mBottomBarLeft;
if (mPosition <= mBottomBarLeft) {
mPosition = mBottomBarLeft;
} else if (mPosition >= mBottomBarRight) {
mPosition = mBottomBarRight;
}
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
5.因为需要左右滑动，所以我们采用GestureDetector的手势滑动管理，判断当用户点击在椭圆中才能让滑动改变
GestureDetector mGestureDetector = new GestureDetector(mContext, new GestureDetector.OnGestureListener() {
@Override
public boolean onSingleTapUp(MotionEvent e) {
if (mWhereClickedState == WHERR_CLICKED_CIRCLE) {
} else if (mWhereClickedState == WHERR_CLICKED_BAR) {
mPosition = (int) Math.round(e.getX() + 0.5);
if (mPosition >= mBottomBarRight) {
mPosition = mBottomBarRight;
} else if (mPosition <= mBottomBarLeft) {
mPosition = mBottomBarLeft;
}
MySeekBar.this.invalidate();
}
return false;
}
@Override
public void onShowPress(MotionEvent e) {
// TODO Auto-generated method stub
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
float distanceY) {
/* if (mWhereClickedState == WHERR_CLICKED_CIRCLE) {*/
mPosition = (int) Math.round(e2.getX() + 0.5);
if (mPosition >= mBottomBarRight) {
mPosition = mBottomBarRight;
} else if (mPosition <= mBottomBarLeft) {
mPosition = mBottomBarLeft;
}
MySeekBar.this.invalidate();
/* } else if (mWhereClickedState == WHERR_CLICKED_BAR) {
}*/
return false;
}
@Override
public void onLongPress(MotionEvent e) {
// TODO Auto-generated method stub
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
// TODO Auto-generated method stub
return false;
}
@Override
public boolean onDown(MotionEvent e) {
float event_x = e.getX();
float event_y = e.getY();
mWhereClickedState = judgeWhereClicked(event_x, event_y);
if (mWhereClickedState == WHERR_CLICKED_VIEW) {
return false;
} else {
return true;
}
}
});
/**
* 判断用户点击位置状态
*
* @param x 用户点击的x坐标
* @param y 用户点击的y坐标
* @return 返回用户点击未知状态：
* WHERR_CLICKED_CIRCLE
* WHERR_CLICKED_BAR
* WHERR_CLICKED_VIEW
*/
public int judgeWhereClicked(float x, float y) {
if (rectF.contains(x, y)) {
return WHERR_CLICKED_CIRCLE; //s_x和s_y界定的区域，即圆圈区域
} else {
return WHERR_CLICKED_VIEW; //view除了上述两部分的部分
}
}
6.现在画东西的笔有了，架子有了，装饰材料有了，只剩往一块白布里面画东西。就成了。 接下来最重要的就是在onDraw方法中，把UI画上去。
@Override
protected void onDraw(Canvas canvas) {
mTopBarRight = mPosition;
mCircleX = mTopBarRight;
mPaint.setColor(mBottomBarColor);
canvas.drawRect(mBottomBarLeft, mBottomBarTop, mBottomBarRight, mBottomBarBottom, mPaint);
mPaint.setColor(mTopBarColor);
canvas.drawRect(mBottomBarLeft, mBottomBarTop, mTopBarRight, mBottomBarBottom, mPaint);
if (mBottomBarRight - mTopBarRight > windows_width / 6 - 10) {//用来防止百分比是100的时候椭圆形画出边界的问题。
aaa = mTopBarRight;
rectF = new RectF(mTopBarRight, dip_size / 2 - dip_size / 5, mTopBarRight + windows_width / 6, dip_size / 2 + dip_size / 5);
canvas.drawRoundRect(rectF,
(windows_width / 6) / 3, //x轴的半径
(windows_width / 6) / 3 - 5, //y轴的半径
paint);//用来画矩形白色背景
canvas.drawRoundRect(rectF,
(windows_width / 6) / 3, //x轴的半径
(windows_width / 6) / 3 - 5, //y轴的半径
whit);//用来画矩形边框
} else {
rectF = new RectF(aaa, dip_size / 2 - dip_size / 5, aaa + windows_width / 6, dip_size / 2 + dip_size / 5);
canvas.drawRoundRect(rectF,
(windows_width / 6) / 3, //x轴的半径
(windows_width / 6) / 3 - 5, //y轴的半径
paint);//用来画矩形白色背景
canvas.drawRoundRect(rectF,
(windows_width / 6) / 3, //x轴的半径
(windows_width / 6) / 3 - 5, //y轴的半径
whit);//用来画矩形边框
}
Paint.FontMetrics fontMetrics = textPaint.getFontMetrics();
float top = fontMetrics.top;//为基线到字体上边框的距离,即上图中的top
float bottom = fontMetrics.bottom;//为基线到字体下边框的距离,即上图中的bottom
int baseLineY = (int) (rectF.centerY() - top / 2 - bottom / 2);//基线中间点的y轴计算公式
canvas.drawText(getProgress() + myText, rectF.centerX(), baseLineY, textPaint);
}
7.获得当前进度由于这个项目是按年或者月显示的，所以获取进度时和设置进度时都需要按照满进度值100来进行换算，设置获得进度的方法getProgress()。
/**
* 获得当前进度值
*
* @return int
*/
public int getProgress() {
float percent = (mPosition - mBottomBarLeft) * 1.0f / (mBottomBarWidth -windows_width/ 6);
if (percent < 0.0) {
percent = 0f;
} else if (percent > 1) {
percent = 1f;
}
int progress = ((int) Math.round(percent * 100 + 0.5) - 1);
if (progress <= 0) {
progress = 1;
} else if (progress > 100) {
progress = 100;
}
if (month) {
return year - (100 - progress);
} else {
return progress / 8 == 0 ? 1 : progress / 8;
}
}
8.项目需要按左右按钮的时候必要你动态设置进度值，并改变椭圆的位置，那么我们只需要改变进度值，然后不断去onDraw重新绘制界面就行了。代码如下
/**
* 通过传入进度值来更新进度条
*/
public void updatePositionFromProgress(int progress) {
if (month) {//按年显示
progress = 100 - (year - progress);//总进度减去今年和传入年份的差值
} else {
//按月显示
progress = (int) (progress * 8.4);
}
float percent = progress / 100f;
if (percent < 0) {
percent = 0.0f;
} else if (percent > 1.0f) {
percent = 1.0f;
}
mPosition = (int) Math.round((mBottomBarWidth -windows_width / 6)* percent + 0.5) + mBottomBarLeft;
if (mPosition <= mBottomBarLeft) {
mPosition = mBottomBarLeft;
} else if (mPosition >= mBottomBarRight) {
mPosition = mBottomBarRight;
}
this.invalidate();
}
#######此时基本的实现已经完成。使用方式基本就是在XML设置颜色，字体之类的事，然后动态去设置进度--->代码如下