新增CommonPagerIndicator，用Drawable控制指示线

Author: hackware1993

app/src/main/java/net/lucode/hackware/magicindicatordemo/ext/indicators/CommonPagerIndicator.java

@@ -0,0 +1,182 @@
+package net.lucode.hackware.magicindicatordemo.ext.indicators;
+
+import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.Rect;
+import android.graphics.drawable.Drawable;
+import android.view.View;
+import android.view.animation.Interpolator;
+import android.view.animation.LinearInterpolator;
+
+import net.lucode.hackware.magicindicator.buildins.commonnavigator.abs.IPagerIndicator;
+import net.lucode.hackware.magicindicator.buildins.commonnavigator.model.PositionData;
+
+import java.util.List;
+
+/**
+ * 通用的indicator，支持外面设置Drawable
+ * Created by hackware on 2016/11/14.
+ */
+
+public class CommonPagerIndicator extends View implements IPagerIndicator {
+    public static final int MODE_MATCH_EDGE = 0;   // drawable宽度 == title宽度 - 2 * mXOffset
+    public static final int MODE_WRAP_CONTENT = 1;    // drawable宽度 == title内容宽度 - 2 * mXOffset
+    public static final int MODE_EXACTLY = 2;
+
+    private int mMode;  // 默认为MODE_MATCH_EDGE模式
+    private Drawable mIndicatorDrawable;
+
+    // 控制动画
+    private Interpolator mStartInterpolator = new LinearInterpolator();
+    private Interpolator mEndInterpolator = new LinearInterpolator();
+
+    private float mDrawableHeight;
+    private float mDrawableWidth;
+    private float mYOffset;
+    private float mXOffset;
+
+    private List<PositionData> mPositionDataList;
+    private Rect mDrawableRect = new Rect();
+
+    public CommonPagerIndicator(Context context) {
+        super(context);
+    }
+
+    @Override
+    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
+        if (mIndicatorDrawable == null) {
+            return;
+        }
+
+        if (mPositionDataList == null || mPositionDataList.isEmpty()) {
+            return;
+        }
+
+        // 计算锚点位置
+        int currentPosition = Math.min(mPositionDataList.size() - 1, position);
+        int nextPosition = Math.min(mPositionDataList.size() - 1, position + 1);
+        PositionData current = mPositionDataList.get(currentPosition);
+        PositionData next = mPositionDataList.get(nextPosition);
+
+        float leftX;
+        float nextLeftX;
+        float rightX;
+        float nextRightX;
+        if (mMode == MODE_MATCH_EDGE) {
+            leftX = current.mLeft + mXOffset;
+            nextLeftX = next.mLeft + mXOffset;
+            rightX = current.mRight - mXOffset;
+            nextRightX = next.mRight - mXOffset;
+            mDrawableRect.top = (int) mYOffset;
+            mDrawableRect.bottom = (int) (getHeight() - mYOffset);
+        } else if (mMode == MODE_WRAP_CONTENT) {
+            leftX = current.mContentLeft + mXOffset;
+            nextLeftX = next.mContentLeft + mXOffset;
+            rightX = current.mContentRight - mXOffset;
+            nextRightX = next.mContentRight - mXOffset;
+            mDrawableRect.top = (int) (current.mContentTop - mYOffset);
+            mDrawableRect.bottom = (int) (current.mContentBottom + mYOffset);
+        } else {    // MODE_EXACTLY
+            leftX = current.mLeft + (current.width() - mDrawableWidth) / 2;
+            nextLeftX = next.mLeft + (next.width() - mDrawableWidth) / 2;
+            rightX = current.mLeft + (current.width() + mDrawableWidth) / 2;
+            nextRightX = next.mLeft + (next.width() + mDrawableWidth) / 2;
+            mDrawableRect.top = (int) (getHeight() - mDrawableHeight - mYOffset);
+            mDrawableRect.bottom = (int) (getHeight() - mYOffset);
+        }
+
+        mDrawableRect.left = (int) (leftX + (nextLeftX - leftX) * mStartInterpolator.getInterpolation(positionOffset));
+        mDrawableRect.right = (int) (rightX + (nextRightX - rightX) * mEndInterpolator.getInterpolation(positionOffset));
+        mIndicatorDrawable.setBounds(mDrawableRect);
+
+        invalidate();
+    }
+
+    @Override
+    public void onPageSelected(int position) {
+    }
+
+    @Override
+    public void onPageScrollStateChanged(int state) {
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        if (mIndicatorDrawable != null) {
+            mIndicatorDrawable.draw(canvas);
+        }
+    }
+
+    @Override
+    public void onPositionDataProvide(List<PositionData> dataList) {
+        mPositionDataList = dataList;
+    }
+
+    public Drawable getIndicatorDrawable() {
+        return mIndicatorDrawable;
+    }
+
+    public void setIndicatorDrawable(Drawable indicatorDrawable) {
+        mIndicatorDrawable = indicatorDrawable;
+    }
+
+    public Interpolator getStartInterpolator() {
+        return mStartInterpolator;
+    }
+
+    public void setStartInterpolator(Interpolator startInterpolator) {
+        mStartInterpolator = startInterpolator;
+    }
+
+    public Interpolator getEndInterpolator() {
+        return mEndInterpolator;
+    }
+
+    public void setEndInterpolator(Interpolator endInterpolator) {
+        mEndInterpolator = endInterpolator;
+    }
+
+    public int getMode() {
+        return mMode;
+    }
+
+    public void setMode(int mode) {
+        if (mode == MODE_EXACTLY || mode == MODE_MATCH_EDGE || mode == MODE_WRAP_CONTENT) {
+            mMode = mode;
+        } else {
+            throw new IllegalArgumentException("mode " + mode + " not supported.");
+        }
+    }
+
+    public float getDrawableHeight() {
+        return mDrawableHeight;
+    }
+
+    public void setDrawableHeight(float drawableHeight) {
+        mDrawableHeight = drawableHeight;
+    }
+
+    public float getDrawableWidth() {
+        return mDrawableWidth;
+    }
+
+    public void setDrawableWidth(float drawableWidth) {
+        mDrawableWidth = drawableWidth;
+    }
+
+    public float getYOffset() {
+        return mYOffset;
+    }
+
+    public void setYOffset(float yOffset) {
+        mYOffset = yOffset;
+    }
+
+    public float getXOffset() {
+        return mXOffset;
+    }
+
+    public void setXOffset(float xOffset) {
+        mXOffset = xOffset;
+    }
+}