This layout currently only supports child views of type {@link MaterialButton}. Buttons can be * added to this view group via XML, as follows: * *
* <com.google.android.material.button.MaterialButtonGroup * xmlns:android="http://schemas.android.com/apk/res/android" * android:id="@+id/toggle_button_group" * android:layout_width="wrap_content" * android:layout_height="wrap_content"> * * <com.google.android.material.button.MaterialButton * android:layout_width="wrap_content" * android:layout_height="wrap_content" * android:text="@string/button_label_private"/> * <com.google.android.material.button.MaterialButton * android:layout_width="wrap_content" * android:layout_height="wrap_content" * android:text="@string/button_label_team"/> * <com.google.android.material.button.MaterialButton * android:layout_width="wrap_content" * android:layout_height="wrap_content" * android:text="@string/button_label_everyone"/> * <com.google.android.material.button.MaterialButton * android:layout_width="wrap_content" * android:layout_height="wrap_content" * android:text="@string/button_label_custom"/> * * </com.google.android.material.button.MaterialButtonGroup> ** *
Buttons can also be added to this view group programmatically via the {@link #addView(View)} * methods. * *
MaterialButtonGroup is a {@link LinearLayout}. Using {@code * android:layout_width="MATCH_PARENT"} and removing {@code android:insetBottom} {@code * android:insetTop} on the children is recommended if using {@code VERTICAL}. * *
For more information, see the component
* developer guidance and design
* guidelines.
*/
public class MaterialButtonGroup extends LinearLayout {
private static final String LOG_TAG = "MButtonGroup";
private static final int DEF_STYLE_RES = R.style.Widget_Material3_MaterialButtonGroup;
private final List It takes the group shape, if specified, as the original state list shape for the first and
* last buttons. Otherwise, it takes the state list shape (or build one from the shape appearance
* model, if state list shape is not specified) in the child button.
*
* @param isFirstVisible Whether this is the first visible child button regardless its index.
* @param isLastVisible Whether this is the last visible child button regardless its index.
* @param index The index of the child button.
*/
@NonNull
private StateListShapeAppearanceModel.Builder getOriginalStateListShapeBuilder(
boolean isFirstVisible, boolean isLastVisible, int index) {
StateListShapeAppearanceModel originalStateList =
groupStateListShapeAppearance != null && (isFirstVisible || isLastVisible)
? groupStateListShapeAppearance
: originalChildStateListShapeAppearanceModels.get(index);
// If the state list shape is not specified, creates one from the shape appearance model.
return originalStateList == null
? new StateListShapeAppearanceModel.Builder(originalChildShapeAppearanceModels.get(index))
: originalStateList.toBuilder();
}
/**
* We keep track of which views are pressed and checked to draw them last. This prevents visual
* issues with overlapping strokes.
*/
@Override
protected int getChildDrawingOrder(int childCount, int i) {
if (childOrder == null || i >= childOrder.length) {
Log.w(LOG_TAG, "Child order wasn't updated");
return i;
}
return childOrder[i];
}
/**
* Sets a negative marginStart on all but the first child, if two adjacent children both have a
* stroke width greater than 0. This prevents a double-width stroke from being drawn for two
* adjacent stroked children, and instead draws the adjacent strokes directly on top of each
* other.
*
* The negative margin adjustment amount will be equal to the smaller of the two adjacent
* stroke widths.
*
* Also rearranges children such that they are shown in the correct visual order.
*/
private void adjustChildMarginsAndUpdateLayout() {
int firstVisibleChildIndex = getFirstVisibleChildIndex();
if (firstVisibleChildIndex == -1) {
return;
}
for (int i = firstVisibleChildIndex + 1; i < getChildCount(); i++) {
// Only adjusts margins if both adjacent children are MaterialButtons
MaterialButton currentButton = getChildButton(i);
MaterialButton previousButton = getChildButton(i - 1);
// Calculates the margin adjustment to be the smaller of the two adjacent stroke widths
int smallestStrokeWidth = 0;
if (spacing <= 0) {
smallestStrokeWidth = min(currentButton.getStrokeWidth(), previousButton.getStrokeWidth());
}
LayoutParams params = buildLayoutParams(currentButton);
if (getOrientation() == HORIZONTAL) {
params.setMarginEnd(0);
params.setMarginStart(spacing - smallestStrokeWidth);
params.topMargin = 0;
} else {
params.bottomMargin = 0;
params.topMargin = spacing - smallestStrokeWidth;
params.setMarginStart(0);
}
currentButton.setLayoutParams(params);
}
resetChildMargins(firstVisibleChildIndex);
}
private void resetChildMargins(int childIndex) {
if (getChildCount() == 0 || childIndex == -1) {
return;
}
MaterialButton currentButton = getChildButton(childIndex);
LayoutParams params = (LayoutParams) currentButton.getLayoutParams();
if (getOrientation() == VERTICAL) {
params.topMargin = 0;
params.bottomMargin = 0;
return;
}
params.setMarginEnd(0);
params.setMarginStart(0);
params.leftMargin = 0;
params.rightMargin = 0;
}
void onButtonWidthChanged(@NonNull MaterialButton button, int increaseSize) {
int buttonIndex = indexOfChild(button);
if (buttonIndex < 0) {
return;
}
MaterialButton prevVisibleButton = getPrevVisibleChildButton(buttonIndex);
MaterialButton nextVisibleButton = getNextVisibleChildButton(buttonIndex);
if (prevVisibleButton == null && nextVisibleButton == null) {
return;
}
if (prevVisibleButton == null) {
nextVisibleButton.setDisplayedWidthDecrease(increaseSize);
}
if (nextVisibleButton == null) {
prevVisibleButton.setDisplayedWidthDecrease(increaseSize);
}
if (prevVisibleButton != null && nextVisibleButton != null) {
// If there are two neighbors, each neighbor will absorb half of the expanded amount.
prevVisibleButton.setDisplayedWidthDecrease(increaseSize / 2);
// We want to avoid one pixel missing due to the casting, when increaseSize is odd.
nextVisibleButton.setDisplayedWidthDecrease((increaseSize + 1) / 2);
}
}
/**
* Adjusts the max amount of size to expand for each child button. So that it won't squeeze its
* neighbors too much to cause text truncation; and the expansion amount per edge is same for all
* buttons,
*/
private void adjustChildSizeChange() {
if (buttonSizeChange == null || getChildCount() == 0) {
return;
}
int firstVisibleChildIndex = getFirstVisibleChildIndex();
int lastVisibleChildIndex = getLastVisibleChildIndex();
int widthIncreaseOnSingleEdge = Integer.MAX_VALUE;
for (int i = firstVisibleChildIndex; i <= lastVisibleChildIndex; i++) {
if (!isChildVisible(i)) {
continue;
}
// Calculates the allowed width increase for each child button with consideration of the max
// allowed width decrease of its neighbors.
int widthIncrease = getButtonAllowedWidthIncrease(i);
// If the button expands on both edges, the width increase on each edge should be half of
// the total width increase. Calculates the minimum width increase on each edge, so that all
// buttons won't squeeze their neighbors too much.
widthIncreaseOnSingleEdge =
min(
widthIncreaseOnSingleEdge,
i != firstVisibleChildIndex && i != lastVisibleChildIndex
? widthIncrease / 2
: widthIncrease);
}
for (int i = firstVisibleChildIndex; i <= lastVisibleChildIndex; i++) {
if (!isChildVisible(i)) {
continue;
}
getChildButton(i).setSizeChange(buttonSizeChange);
// If the button expands on both edges, the total width increase should be double of the
// width increase on each edge.
getChildButton(i)
.setWidthChangeMax(
i == firstVisibleChildIndex || i == lastVisibleChildIndex
? widthIncreaseOnSingleEdge
: widthIncreaseOnSingleEdge * 2);
}
}
/**
* Returns the allowed width increase for a child button.
*
* The allowed width increase is the smaller amount of the max width increase of the button in
* all states and the total allowed width decrease of its neighbors.
*/
private int getButtonAllowedWidthIncrease(int index) {
if (!isChildVisible(index) || buttonSizeChange == null) {
return 0;
}
MaterialButton currentButton = getChildButton(index);
int widthIncrease = max(0, buttonSizeChange.getMaxWidthChange(currentButton.getWidth()));
// Checking neighbors' allowed width decrease.
MaterialButton prevVisibleButton = getPrevVisibleChildButton(index);
int prevButtonAllowedWidthDecrease =
prevVisibleButton == null ? 0 : prevVisibleButton.getAllowedWidthDecrease();
MaterialButton nextVisibleButton = getNextVisibleChildButton(index);
int nextButtonAllowedWidthDecrease =
nextVisibleButton == null ? 0 : nextVisibleButton.getAllowedWidthDecrease();
return min(widthIncrease, prevButtonAllowedWidthDecrease + nextButtonAllowedWidthDecrease);
}
// ================ Getters and setters ===================
/**
* Returns the {@link StateListSizeChange} of child buttons on state changes.
*
* @hide
*/
@RestrictTo(Scope.LIBRARY_GROUP)
@Nullable
public StateListSizeChange getButtonSizeChange() {
return buttonSizeChange;
}
/**
* Sets the {@link StateListSizeChange} of child buttons on state changes.
*
* @param buttonSizeChange The new {@link StateListSizeChange} of child buttons.
* @hide
*/
@RestrictTo(Scope.LIBRARY_GROUP)
public void setButtonSizeChange(@NonNull StateListSizeChange buttonSizeChange) {
if (this.buttonSizeChange != buttonSizeChange) {
this.buttonSizeChange = buttonSizeChange;
adjustChildSizeChange();
requestLayout();
invalidate();
}
}
/** Returns the spacing (in pixels) between each button in the group. */
@Px
public int getSpacing() {
return spacing;
}
/**
* Sets the spacing between each button in the group.
*
* @param spacing the spacing (in pixels) between each button in the group
*/
public void setSpacing(@Px int spacing) {
this.spacing = spacing;
invalidate();
requestLayout();
}
/** Returns the inner corner size of the group. */
@NonNull
public CornerSize getInnerCornerSize() {
return innerCornerSize.getDefaultCornerSize();
}
/**
* Sets the inner corner size of the group.
*
* Can set as an {@link AbsoluteCornerSize} or {@link RelativeCornerSize}. Don't set relative
* corner size larger than 50% or absolute corner size larger than half height to avoid corner
* overlapping.
*
* @param cornerSize the inner corner size of the group
*/
public void setInnerCornerSize(@NonNull CornerSize cornerSize) {
innerCornerSize = StateListCornerSize.create(cornerSize);
isChildrenShapeInvalidated = true;
updateChildShapes();
invalidate();
}
/**
* Returns the inner corner size state list of the group.
*
* @hide
*/
@NonNull
@RestrictTo(Scope.LIBRARY_GROUP)
public StateListCornerSize getInnerCornerSizeStateList() {
return innerCornerSize;
}
/**
* Sets the inner corner size state list of the group.
*
* Can set as an {@link StateListCornerSize}. Don't set relative corner size larger than 50% or
* absolute corner size larger than half height to the corner size in any state to avoid corner
* overlapping.
*
* @param cornerSizeStateList the inner corner size state list of the group
* @hide
*/
@RestrictTo(Scope.LIBRARY_GROUP)
public void setInnerCornerSizeStateList(@NonNull StateListCornerSize cornerSizeStateList) {
innerCornerSize = cornerSizeStateList;
isChildrenShapeInvalidated = true;
updateChildShapes();
invalidate();
}
/** Returns the {@link ShapeAppearanceModel} of the group. */
@Nullable
public ShapeAppearanceModel getShapeAppearance() {
return groupStateListShapeAppearance == null
? null
: groupStateListShapeAppearance.getDefaultShape(/* withCornerSizeOverrides= */ true);
}
/**
* Sets the {@link ShapeAppearanceModel} of the group.
*
* @param shapeAppearance The new {@link ShapeAppearanceModel} of the group.
*/
public void setShapeAppearance(@Nullable ShapeAppearanceModel shapeAppearance) {
groupStateListShapeAppearance =
new StateListShapeAppearanceModel.Builder(shapeAppearance).build();
isChildrenShapeInvalidated = true;
updateChildShapes();
invalidate();
}
/**
* Returns the {@link StateListShapeAppearanceModel} of the group.
*
* @hide
*/
@Nullable
@RestrictTo(Scope.LIBRARY_GROUP)
public StateListShapeAppearanceModel getStateListShapeAppearance() {
return groupStateListShapeAppearance;
}
/**
* Sets the {@link StateListShapeAppearanceModel} of the group.
*
* @param stateListShapeAppearance The new {@link StateListShapeAppearanceModel} of the group.
* @hide
*/
@RestrictTo(Scope.LIBRARY_GROUP)
public void setStateListShapeAppearance(
@Nullable StateListShapeAppearanceModel stateListShapeAppearance) {
groupStateListShapeAppearance = stateListShapeAppearance;
isChildrenShapeInvalidated = true;
updateChildShapes();
invalidate();
}
// ================ Helper functions ===================
@NonNull
MaterialButton getChildButton(int index) {
return (MaterialButton) getChildAt(index);
}
@NonNull
LinearLayout.LayoutParams buildLayoutParams(@NonNull View child) {
ViewGroup.LayoutParams layoutParams = child.getLayoutParams();
if (layoutParams instanceof LinearLayout.LayoutParams) {
return (LayoutParams) layoutParams;
}
return new LayoutParams(layoutParams.width, layoutParams.height);
}
private int getFirstVisibleChildIndex() {
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
if (isChildVisible(i)) {
return i;
}
}
return -1;
}
private int getLastVisibleChildIndex() {
int childCount = getChildCount();
for (int i = childCount - 1; i >= 0; i--) {
if (isChildVisible(i)) {
return i;
}
}
return -1;
}
private boolean isChildVisible(int i) {
View child = getChildAt(i);
return child.getVisibility() != View.GONE;
}
private void setGeneratedIdIfNeeded(@NonNull MaterialButton materialButton) {
// Generates an ID if none is set, for relative positioning purposes
if (materialButton.getId() == View.NO_ID) {
materialButton.setId(View.generateViewId());
}
}
@Nullable
private MaterialButton getNextVisibleChildButton(int index) {
int childCount = getChildCount();
for (int i = index + 1; i < childCount; i++) {
if (isChildVisible(i)) {
return getChildButton(i);
}
}
return null;
}
@Nullable
private MaterialButton getPrevVisibleChildButton(int index) {
for (int i = index - 1; i >= 0; i--) {
if (isChildVisible(i)) {
return getChildButton(i);
}
}
return null;
}
private void updateChildOrder() {
final SortedMap