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class SlidingTabStrip extends LinearLayout {
private static final int DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS = 2;
private static final byte DEFAULT_BOTTOM_BORDER_COLOR_ALPHA = 0x26;
private static final int SELECTED_INDICATOR_THICKNESS_DIPS = 8;
private static final int DEFAULT_SELECTED_INDICATOR_COLOR = 0xFF33B5E5;
private static final int DEFAULT_DIVIDER_THICKNESS_DIPS = 1;
private static final byte DEFAULT_DIVIDER_COLOR_ALPHA = 0x20;
private static final float DEFAULT_DIVIDER_HEIGHT = 0.5f;
private final int mBottomBorderThickness;
private final Paint mBottomBorderPaint;
private final int mSelectedIndicatorThickness;
private final Paint mSelectedIndicatorPaint;
private final int mDefaultBottomBorderColor;
private final Paint mDividerPaint;
private final float mDividerHeight;
private int mSelectedPosition;
private float mSelectionOffset;
private SlidingTabLayout.TabColorizer mCustomTabColorizer;
private final SimpleTabColorizer mDefaultTabColorizer;
SlidingTabStrip(Context context) {
this(context, null);
}
SlidingTabStrip(Context context, AttributeSet attrs) {
super(context, attrs);
setWillNotDraw(false);
final float density = getResources().getDisplayMetrics().density;
TypedValue outValue = new TypedValue();
context.getTheme().resolveAttribute(R.attr.colorForeground, outValue, true);
final int themeForegroundColor = outValue.data;
mDefaultBottomBorderColor = setColorAlpha(themeForegroundColor,
DEFAULT_BOTTOM_BORDER_COLOR_ALPHA);
mDefaultTabColorizer = new SimpleTabColorizer();
mDefaultTabColorizer.setIndicatorColors(DEFAULT_SELECTED_INDICATOR_COLOR);
mDefaultTabColorizer.setDividerColors(setColorAlpha(themeForegroundColor,
DEFAULT_DIVIDER_COLOR_ALPHA));
mBottomBorderThickness = (int) (DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS * density);
mBottomBorderPaint = new Paint();
mBottomBorderPaint.setColor(mDefaultBottomBorderColor);
mSelectedIndicatorThickness = (int) (SELECTED_INDICATOR_THICKNESS_DIPS * density);
mSelectedIndicatorPaint = new Paint();
mDividerHeight = DEFAULT_DIVIDER_HEIGHT;
mDividerPaint = new Paint();
mDividerPaint.setStrokeWidth((int) (DEFAULT_DIVIDER_THICKNESS_DIPS * density));
}
void setCustomTabColorizer(SlidingTabLayout.TabColorizer customTabColorizer) {
mCustomTabColorizer = customTabColorizer;
invalidate();
}
void setSelectedIndicatorColors(int... colors) {
// Make sure that the custom colorizer is removed
mCustomTabColorizer = null;
mDefaultTabColorizer.setIndicatorColors(colors);
invalidate();
}
void setDividerColors(int... colors) {
// Make sure that the custom colorizer is removed
mCustomTabColorizer = null;
mDefaultTabColorizer.setDividerColors(colors);
invalidate();
}
void onViewPagerPageChanged(int position, float positionOffset) {
mSelectedPosition = position;
mSelectionOffset = positionOffset;
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
final int height = getHeight();
final int childCount = getChildCount();
final int dividerHeightPx = (int) (Math.min(Math.max(0f, mDividerHeight), 1f) * height);
final SlidingTabLayout.TabColorizer tabColorizer = mCustomTabColorizer != null
? mCustomTabColorizer
: mDefaultTabColorizer;
// Thick colored underline below the current selection
if (childCount > 0) {
View selectedTitle = getChildAt(mSelectedPosition);
int left = selectedTitle.getLeft();
int right = selectedTitle.getRight();
int color = tabColorizer.getIndicatorColor(mSelectedPosition);
if (mSelectionOffset > 0f && mSelectedPosition < (getChildCount() - 1)) {
int nextColor = tabColorizer.getIndicatorColor(mSelectedPosition + 1);
if (color != nextColor) {
color = blendColors(nextColor, color, mSelectionOffset);
}
// Draw the selection partway between the tabs
View nextTitle = getChildAt(mSelectedPosition + 1);
left = (int) (mSelectionOffset * nextTitle.getLeft() +
(1.0f - mSelectionOffset) * left);
right = (int) (mSelectionOffset * nextTitle.getRight() +
(1.0f - mSelectionOffset) * right);
}
mSelectedIndicatorPaint.setColor(color);
canvas.drawRect(left, height - mSelectedIndicatorThickness, right,
height, mSelectedIndicatorPaint);
}
// Thin underline along the entire bottom edge
canvas.drawRect(0, height - mBottomBorderThickness, getWidth(), height, mBottomBorderPaint);
// Vertical separators between the titles
int separatorTop = (height - dividerHeightPx) / 2;
for (int i = 0; i < childCount - 1; i++) {
View child = getChildAt(i);
mDividerPaint.setColor(tabColorizer.getDividerColor(i));
canvas.drawLine(child.getRight(), separatorTop, child.getRight(),
separatorTop + dividerHeightPx, mDividerPaint);
}
}
/**
* Set the alpha value of the {@code color} to be the given {@code alpha} value.
*/
private static int setColorAlpha(int color, byte alpha) {
return Color.argb(alpha, Color.red(color), Color.green(color), Color.blue(color));
}
/**
* Blend {@code color1} and {@code color2} using the given ratio.
*
* @param ratio of which to blend. 1.0 will return {@code color1}, 0.5 will give an even blend,
* 0.0 will return {@code color2}.
*/
private static int blendColors(int color1, int color2, float ratio) {
final float inverseRation = 1f - ratio;
float r = (Color.red(color1) * ratio) + (Color.red(color2) * inverseRation);
float g = (Color.green(color1) * ratio) + (Color.green(color2) * inverseRation);
float b = (Color.blue(color1) * ratio) + (Color.blue(color2) * inverseRation);
return Color.rgb((int) r, (int) g, (int) b);
}
private static class SimpleTabColorizer implements SlidingTabLayout.TabColorizer {
private int[] mIndicatorColors;
private int[] mDividerColors;
@Override
public final int getIndicatorColor(int position) {
return mIndicatorColors[position % mIndicatorColors.length];
}
@Override
public final int getDividerColor(int position) {
return mDividerColors[position % mDividerColors.length];
}
void setIndicatorColors(int... colors) {
mIndicatorColors = colors;
}
void setDividerColors(int... colors) {
mDividerColors = colors;
}
}
}
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