android 原生的seekbar只能單向選擇滑動，當專案需要選取範圍的時候，這明顯是不能夠滿足要求的。所以就得自己實現一個雙向滑動的Seekbar了，就取名為DoubleSeekBar吧。 而自定義View由是Android知識點中必須掌握的技能所以，這裡就寫一下自己的實現吧。著急的同學，可以直接拷貝程式碼直接使用。 由於佈局比較簡單，這裡直接繼承View，然後重寫onLayout(),onMeasure(),onDraw()方法，程式碼裡註釋比較齊全，想多瞭解的，可以看著註釋理解下。 程式碼如下：
public class DoubleSeekBar extends View {
private static final String TAG = "DoubleSeekBar";
private static final int CLICK_TYPE_NULL = 0;
private static final int CLICK_TYPE_LEFT = 1;
private static final int CLICK_TYPE_RIGHT = 2;
private Bitmap leftIcon;
private Bitmap rightIcon;
private Bitmap clickIcon;
private int maxValue;//最大值
private int minValue;//最小值
private int leftValue, rightValue;
private int defaultWidth = 0;
private int defaultHeight = 0;
private float bgHeight;
private float paddingLeft, paddingRight;
private float indexLeftX, indexLeftY;//左按鈕的座標值
private float indexRightX, indexRightY;//右按鈕的座標值
private int viewWidth, viewHeight;
private float startLeftX, startRightX;//左右按鈕的開始x軸座標值
private int clickedType = CLICK_TYPE_NULL;//0 沒有點選，1點選中左按鈕，2點選中右按鈕
private Paint paintBg = new Paint(Paint.ANTI_ALIAS_FLAG);
private Paint paintBg2 = new Paint(Paint.ANTI_ALIAS_FLAG);
private Paint iconPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
private OnChanged mOnChanged;
public DoubleSeekBar(Context context) {
this(context, null);
}
public DoubleSeekBar(Context context, @Nullable AttributeSet attrs) {
this(context, attrs, 0);
}
public DoubleSeekBar(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
bgHeight = UIUtil.dp2px(context, 2);//設定背景線條的高度
leftIcon = getBitmap(R.drawable.double_seek_bar_icon);
rightIcon = getBitmap(R.drawable.double_seek_bar_icon);
clickIcon = getBitmap(R.drawable.double_seek_bar_click_icon);
paddingLeft = UIUtil.dp2px(context, 16);
paddingRight = UIUtil.dp2px(context, 16);
paintBg.setColor(getResources().getColor(R.color.md_red_A400));
paintBg2.setColor(getResources().getColor(R.color.md_grey_400));
maxValue = 100;//default maxvalue
minValue = 0;//default minvalue
leftValue = minValue;
rightValue = maxValue;
defaultWidth = UIUtil.dp2px(context, 100);
defaultHeight = UIUtil.dp2px(context, 50);
setLayerType(LAYER_TYPE_SOFTWARE, null);
}
private Bitmap getBitmap(int drawableRes) {
Drawable drawable = getResources().getDrawable(drawableRes);
Canvas canvas = new Canvas();
Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
canvas.setBitmap(bitmap);
drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());
drawable.draw(canvas);
return bitmap;
}
public void setMaxValue(int maxValue) {
if (maxValue < 0) {
maxValue = 0;
}
this.maxValue = maxValue;
}
public void setMinValue(int minValue) {
if (minValue < 0) {
minValue = 0;
}
this.minValue = minValue;
}
public void setOnChanged(OnChanged mOnChanged) {
this.mOnChanged = mOnChanged;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (isClickedIcon(event)) {
postInvalidate();
return true;
}
break;
case MotionEvent.ACTION_UP:
clickedType = CLICK_TYPE_NULL;
postInvalidate();
break;
case MotionEvent.ACTION_MOVE:
if (handleMoveEvent(event)) {
return true;
}
break;
default:
break;
}
return super.onTouchEvent(event);
}
/**
* 判斷是否點選到按鈕了
*
* @param event
* @return
*/
private boolean isClickedIcon(MotionEvent event) {
float x = event.getX();
float y = event.getY();
if (x < indexLeftX + leftIcon.getWidth() && x > indexLeftX && y > indexLeftY && y < indexLeftY + leftIcon.getHeight()) {
clickedType = CLICK_TYPE_LEFT;
return true;
}
if (x < indexRightX + rightIcon.getWidth() && x > indexRightX && y > indexRightY && y < indexRightY + rightIcon.getHeight()) {
clickedType = CLICK_TYPE_RIGHT;
return true;
}
clickedType = CLICK_TYPE_NULL;
return false;
}
/**
* 滑動事件處理
*
* @param motionEvent
*/
private boolean handleMoveEvent(MotionEvent motionEvent) {
Log.d(TAG, "handleMoveEvent: start");
float x = motionEvent.getX();
if (clickedType == CLICK_TYPE_LEFT) {
if (x < indexRightX - leftIcon.getWidth() && x > startLeftX) {//左按鈕的範圍小於右按鈕的位置，大於初始值位置
indexLeftX = x;
}
Log.d(TAG, "handleMoveEvent: start indexLeftX = " + indexLeftX);
} else if (clickedType == CLICK_TYPE_RIGHT) {
if (x > indexLeftX + rightIcon.getWidth() && x < startRightX) {//右按鈕的範圍大於左按鈕的位置，小於初始值位置
indexRightX = x;
}
Log.d(TAG, "handleMoveEvent: start indexRightX = " + indexRightX);
}
leftValue = (int) ((maxValue - minValue) * (indexLeftX - startLeftX) / (startRightX - startLeftX));
rightValue = (int) ((maxValue - minValue) * (indexRightX - startLeftX) / (startRightX - startLeftX));
if (mOnChanged != null) {
mOnChanged.onChange(leftValue, rightValue);
}
Log.d(TAG, "handleMoveEvent: start leftValue = " + leftValue + " rightValue = " + rightValue);
postInvalidate();
return true;
}
@Override
protected void onFinishInflate() {
super.onFinishInflate();
}
/**
* 注意，在LinearLayout佈局中，設定weight = 1時，onlayout 會多次回撥，導致indexL(/R)X值一直為預設值，導致無法滑動
* 可以將佈局改成releativeLayout。
* @param changed
* @param left
* @param top
* @param right
* @param bottom
*/
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
Log.d(TAG, "onLayout: ");
viewWidth = getWidth();
viewHeight = getHeight();
//左右按鈕的初始值位置計算
startLeftX = 0 + paddingLeft - leftIcon.getWidth() / 2;
indexLeftX = startLeftX;
indexLeftY = viewHeight / 2 - bgHeight / 2 - leftIcon.getHeight() / 2;
startRightX = viewWidth - paddingRight - rightIcon.getWidth() / 2;
indexRightX = startRightX;
indexRightY = viewHeight / 2 - bgHeight / 2 - rightIcon.getHeight() / 2;
leftValue = (int) ((maxValue - minValue) * (indexLeftX - startLeftX) / (startRightX - startLeftX));
rightValue = (int) ((maxValue - minValue) * (indexRightX - startLeftX) / (startRightX - startLeftX));
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Log.d(TAG, "onDraw: getWidth = " + viewWidth);
drawBg(canvas);
drawLeftIcon(canvas);
drawRightIcon(canvas);
}
/**
* 繪製背景
*
* @param canvas
*/
private void drawBg(Canvas canvas) {
paintBg.setAntiAlias(true);
//畫兩端的半圓
float circleLeftCenterX = 0 + paddingLeft;
float circleRightCenterX = viewWidth - paddingRight;
canvas.drawCircle(circleLeftCenterX, viewHeight / 2, bgHeight / 2, paintBg);
canvas.drawCircle(circleRightCenterX, viewHeight / 2, bgHeight / 2, paintBg);
canvas.drawRect(
new RectF(circleLeftCenterX, viewHeight / 2 - bgHeight / 2, circleRightCenterX, viewHeight / 2 + bgHeight / 2)
, paintBg);
//左右按鈕滑動區域之外繪製其他顏色
int centerLeftIconX = (int) (indexLeftX + leftIcon.getWidth() / 2);//左按鈕圖示的中心點
int centerRightIconX = (int) (indexRightX + rightIcon.getWidth() / 2);//右按鈕圖示的中心點
if (centerLeftIconX > circleLeftCenterX) {
canvas.drawCircle(circleLeftCenterX, viewHeight / 2, bgHeight / 2, paintBg2);
canvas.drawRect(
new RectF(circleLeftCenterX, viewHeight / 2 - bgHeight / 2, centerLeftIconX, viewHeight / 2 + bgHeight / 2)
, paintBg2);
}
if (centerRightIconX < circleRightCenterX) {
canvas.drawCircle(circleRightCenterX, viewHeight / 2, bgHeight / 2, paintBg2);
canvas.drawRect(
new RectF(centerRightIconX, viewHeight / 2 - bgHeight / 2, circleRightCenterX, viewHeight / 2 + bgHeight / 2)
, paintBg2);
}
}
/**
* 繪製左按鈕
* @param canvas
*/
private void drawLeftIcon(Canvas canvas) {
if (clickedType == CLICK_TYPE_LEFT) {
iconPaint.setMaskFilter(new BlurMaskFilter(50, BlurMaskFilter.Blur.INNER));
canvas.drawBitmap(clickIcon, indexLeftX, indexLeftY, iconPaint);
} else {
iconPaint.setMaskFilter(null);
canvas.drawBitmap(leftIcon, indexLeftX, indexLeftY, iconPaint);
}
}
/**
* 繪製右按鈕
* @param canvas
*/
private void drawRightIcon(Canvas canvas) {
Log.d(TAG, "drawLeftIcon: getWidht = " + viewWidth + " indexRightX= " + indexRightX + " indexRightY = " + indexRightY);
if (clickedType == CLICK_TYPE_RIGHT) {
iconPaint.setMaskFilter(new BlurMaskFilter(50, BlurMaskFilter.Blur.INNER));
canvas.drawBitmap(clickIcon, indexRightX, indexRightY, iconPaint);
} else {
iconPaint.setMaskFilter(null);
canvas.drawBitmap(rightIcon, indexRightX, indexRightY, iconPaint);
}
}
/**
* 回撥介面，回撥左右值
*/
public interface OnChanged {
void onChange(int leftValue, int rightValue);
}
/**
* 重寫onMeasure方法，設定wrap_content 時需要預設大小
*
* @param widthMeasureSpec
* @param heightMeasureSpec
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);
int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSpecSize = MeasureSpec.getSize(heightMeasureSpec);
if (widthSpecMode == MeasureSpec.AT_MOST && heightSpecMode == MeasureSpec.AT_MOST) {
setMeasuredDimension(defaultWidth, defaultHeight);
} else if (widthSpecMode == MeasureSpec.AT_MOST) {
setMeasuredDimension(defaultWidth, heightSpecSize);
} else if (heightSpecMode == MeasureSpec.AT_MOST) {
setMeasuredDimension(widthSpecSize, defaultHeight);
}
}
}
複製程式碼左右按鈕的Drawable xml佈局（一個正常狀態的，一個按壓狀態的）如下： double_seek_bar_click_icon.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape android:shape="oval">
<solid android:color="@color/md_red_A700" />
<size android:width="12dp" android:height="12dp"></size>
</shape>
</item>
</selector>
複製程式碼double_seek_bar_icon.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape android:shape="oval">
<solid android:color="@color/md_red_A400" />
<size android:width="12dp" android:height="12dp"></size>
</shape>
</item>
</selector>
複製程式碼使用：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_personal_center);
final TextView txtLeft = findViewById(R.id.txt_left);
final TextView txtRight = findViewById(R.id.txt_right);
DoubleSeekBar doubleSeekBar = findViewById(R.id.double_seek_bar);
doubleSeekBar.setMinValue(0);
doubleSeekBar.setMaxValue(100);
doubleSeekBar.setOnChanged(new DoubleSeekBar.OnChanged() {
@Override
public void onChange(int leftValue, int rightValue) {
txtLeft.setText(String.valueOf(leftValue));
txtRight.setText(String.valueOf(rightValue));
}
});
}
複製程式碼效果如下：
