Add TextDrawableHelper, a class that helps drawables support drawing …

…text.

PiperOrigin-RevId: 235979500

lib/java/com/google/android/material/internal/TextDrawableHelper.java

@@ -0,0 +1,158 @@
+/*
+ * Copyright 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.android.material.internal;
+
+import static androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP;
+
+import android.content.Context;
+import android.graphics.Paint;
+import android.graphics.Typeface;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.RestrictTo;
+import com.google.android.material.resources.TextAppearance;
+import com.google.android.material.resources.TextAppearanceFontCallback;
+import android.text.TextPaint;
+import java.lang.ref.WeakReference;
+
+/**
+ * Class that helps to support drawing text in drawables. It can be used by any drawable that draws
+ * text.
+ *
+ * @hide
+ */
+@RestrictTo(LIBRARY_GROUP)
+public class TextDrawableHelper {
+
+ private final TextPaint textPaint = new TextPaint(Paint.ANTI_ALIAS_FLAG);
+
+ private final TextAppearanceFontCallback fontCallback =
+ new TextAppearanceFontCallback() {
+ @Override
+ public void onFontRetrieved(@NonNull Typeface typeface, boolean fontResolvedSynchronously) {
+ if (fontResolvedSynchronously) {
+ return;
+ }
+ textWidthDirty = true;
+ TextDrawableDelegate textDrawableDelegate = delegate.get();
+ if (textDrawableDelegate != null) {
+ textDrawableDelegate.onTextSizeChange();
+ }
+ }
+
+ @Override
+ public void onFontRetrievalFailed(int reason) {
+ textWidthDirty = true;
+ // Use fallback font.
+ TextDrawableDelegate textDrawableDelegate = delegate.get();
+ if (textDrawableDelegate != null) {
+ textDrawableDelegate.onTextSizeChange();
+ }
+ }
+ };
+
+ private float textWidth;
+ private boolean textWidthDirty = true;
+ private WeakReference<TextDrawableDelegate> delegate = new WeakReference<>(null);
+ @Nullable private TextAppearance textAppearance;
+
+ /** Sets the delegate that owns this TextDrawableHelper. */
+ public void setDelegate(@Nullable TextDrawableDelegate delegate) {
+ this.delegate = new WeakReference<>(delegate);
+ }
+
+ public TextPaint getTextPaint() {
+ return textPaint;
+ }
+
+ public void setTextWidthDirty(boolean dirty) {
+ textWidthDirty = dirty;
+ }
+
+ public boolean isTextWidthDirty() {
+ return textWidthDirty;
+ }
+
+ /** Returns the visual width of the {@code text} based on its current text appearance. */
+ public float getTextWidth(String text) {
+ if (!textWidthDirty) {
+ return textWidth;
+ }
+
+ textWidth = calculateTextWidth(text);
+ textWidthDirty = false;
+ return textWidth;
+ }
+
+ private float calculateTextWidth(@Nullable CharSequence charSequence) {
+ if (charSequence == null) {
+ return 0f;
+ }
+ return textPaint.measureText(charSequence, 0, charSequence.length());
+ }
+
+ /**
+ * Returns the text appearance.
+ *
+ * @see #setTextAppearance(TextAppearance, Context)
+ */
+ public TextAppearance getTextAppearance() {
+ return textAppearance;
+ }
+
+ /**
+ * Sets the delegate drawable's text appearance. If the {@code textAppearance} is {@code null},
+ * text appearance will be cleared.
+ *
+ * @param textAppearance The delegate drawable's text appearance or null to clear it.
+ * @see #getTextAppearance()
+ */
+ public void setTextAppearance(@Nullable TextAppearance textAppearance, Context context) {
+ if (this.textAppearance != textAppearance) {
+ this.textAppearance = textAppearance;
+ if (textAppearance != null) {
+ textAppearance.updateMeasureState(context, textPaint, fontCallback);
+
+ TextDrawableDelegate textDrawableDelegate = delegate.get();
+ if (textDrawableDelegate != null) {
+ textPaint.drawableState = textDrawableDelegate.getState();
+ }
+ textAppearance.updateDrawState(context, textPaint, fontCallback);
+ textWidthDirty = true;
+ }
+
+ TextDrawableDelegate textDrawableDelegate = delegate.get();
+ if (textDrawableDelegate != null) {
+ textDrawableDelegate.onTextSizeChange();
+ textDrawableDelegate.onStateChange(textDrawableDelegate.getState());
+ }
+ }
+ }
+
+ /** Delegate interface to be implemented by Drawables that own a TextDrawableHelper. */
+ public interface TextDrawableDelegate {
+ // See Drawable#getState()
+ @NonNull
+ int[] getState();
+
+ /** Handles a change in the text's size. */
+ void onTextSizeChange();
+
+ // See Drawable#onStateChange();
+ boolean onStateChange(int[] state);
+ }
+}