Text view that auto adjusts text size to fit within the view.If the text size equals the minimum text size and still does not

fit, append with an ellipsis.

Author: daniloercoli

WordPressUtils/src/main/java/org/wordpress/android/util/AutoResizeTextView.java

@@ -0,0 +1,299 @@
+package org.wordpress.android.util;
+
+import android.content.Context;
+import android.text.Layout;
+import android.text.StaticLayout;
+import android.text.TextPaint;
+import android.util.AttributeSet;
+import android.util.TypedValue;
+import android.widget.TextView;
+
+/**
+ * Text view that auto adjusts text size to fit within the view.
+ * If the text size equals the minimum text size and still does not
+ * fit, append with an ellipsis.
+ *
+ * See http://stackoverflow.com/a/5535672
+ *
+ */
+public class AutoResizeTextView extends TextView {
+    // Minimum text size for this text view
+    public static final float MIN_TEXT_SIZE = 20;
+
+    // Interface for resize notifications
+    public interface OnTextResizeListener {
+        void onTextResize(TextView textView, float oldSize, float newSize);
+    }
+
+    // Our ellipse string
+    private static final String M_ELLIPSIS = "...";
+
+    // Registered resize listener
+    private OnTextResizeListener mTextResizeListener;
+
+    // Flag for text and/or size changes to force a resize
+    private boolean mNeedsResize = false;
+
+    // Text size that is set from code. This acts as a starting point for resizing
+    private float mTextSize;
+
+    // Temporary upper bounds on the starting text size
+    private float mMaxTextSize = 0;
+
+    // Lower bounds for text size
+    private float mMinTextSize = MIN_TEXT_SIZE;
+
+    // Text view line spacing multiplier
+    private float mSpacingMult = 1.0f;
+
+    // Text view additional line spacing
+    private float mSpacingAdd = 0.0f;
+
+    // Add ellipsis to text that overflows at the smallest text size
+    private boolean mAddEllipsis = true;
+
+    // Default constructor override
+    public AutoResizeTextView(Context context) {
+        this(context, null);
+    }
+
+    // Default constructor when inflating from XML file
+    public AutoResizeTextView(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    // Default constructor override
+    public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+        mTextSize = getTextSize();
+    }
+
+    /**
+     * When text changes, set the force resize flag to true and reset the text size.
+     */
+    @Override
+    protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) {
+        mNeedsResize = true;
+        // Since this view may be reused, it is good to reset the text size
+        resetTextSize();
+    }
+
+    /**
+     * If the text view size changed, set the force resize flag to true
+     */
+    @Override
+    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
+        if (w != oldw || h != oldh) {
+            mNeedsResize = true;
+        }
+    }
+
+    /**
+     * Register listener to receive resize notifications
+     * @param listener
+     */
+    public void setOnResizeListener(OnTextResizeListener listener) {
+        mTextResizeListener = listener;
+    }
+
+    /**
+     * Override the set text size to update our internal reference values
+     */
+    @Override
+    public void setTextSize(float size) {
+        super.setTextSize(size);
+        mTextSize = getTextSize();
+    }
+
+    /**
+     * Override the set text size to update our internal reference values
+     */
+    @Override
+    public void setTextSize(int unit, float size) {
+        super.setTextSize(unit, size);
+        mTextSize = getTextSize();
+    }
+
+    /**
+     * Override the set line spacing to update our internal reference values
+     */
+    @Override
+    public void setLineSpacing(float add, float mult) {
+        super.setLineSpacing(add, mult);
+        mSpacingMult = mult;
+        mSpacingAdd = add;
+    }
+
+    /**
+     * Set the upper text size limit and invalidate the view
+     * @param maxTextSize
+     */
+    public void setMaxTextSize(float maxTextSize) {
+        mMaxTextSize = maxTextSize;
+        requestLayout();
+        invalidate();
+    }
+
+    /**
+     * Return upper text size limit
+     * @return
+     */
+    public float getMaxTextSize() {
+        return mMaxTextSize;
+    }
+
+    /**
+     * Set the lower text size limit and invalidate the view
+     * @param minTextSize
+     */
+    public void setMinTextSize(float minTextSize) {
+        mMinTextSize = minTextSize;
+        requestLayout();
+        invalidate();
+    }
+
+    /**
+     * Return lower text size limit
+     * @return
+     */
+    public float getMinTextSize() {
+        return mMinTextSize;
+    }
+
+    /**
+     * Set flag to add ellipsis to text that overflows at the smallest text size
+     * @param addEllipsis
+     */
+    public void setAddEllipsis(boolean addEllipsis) {
+        mAddEllipsis = addEllipsis;
+    }
+
+    /**
+     * Return flag to add ellipsis to text that overflows at the smallest text size
+     * @return
+     */
+    public boolean getAddEllipsis() {
+        return mAddEllipsis;
+    }
+
+    /**
+     * Reset the text to the original size
+     */
+    public void resetTextSize() {
+        if (mTextSize > 0) {
+            super.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize);
+            mMaxTextSize = mTextSize;
+        }
+    }
+
+    /**
+     * Resize text after measuring
+     */
+    @Override
+    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
+        if (changed || mNeedsResize) {
+            int widthLimit = (right - left) - getCompoundPaddingLeft() - getCompoundPaddingRight();
+            int heightLimit = (bottom - top) - getCompoundPaddingBottom() - getCompoundPaddingTop();
+            resizeText(widthLimit, heightLimit);
+        }
+        super.onLayout(changed, left, top, right, bottom);
+    }
+
+    /**
+     * Resize the text size with default width and height
+     */
+    public void resizeText() {
+        int heightLimit = getHeight() - getPaddingBottom() - getPaddingTop();
+        int widthLimit = getWidth() - getPaddingLeft() - getPaddingRight();
+        resizeText(widthLimit, heightLimit);
+    }
+
+    /**
+     * Resize the text size with specified width and height
+     * @param width
+     * @param height
+     */
+    public void resizeText(int width, int height) {
+        CharSequence text = getText();
+        // Do not resize if the view does not have dimensions or there is no text
+        if (text == null || text.length() == 0 || height <= 0 || width <= 0 || mTextSize == 0) {
+            return;
+        }
+
+        // Get the text view's paint object
+        TextPaint textPaint = getPaint();
+
+        // Store the current text size
+        float oldTextSize = textPaint.getTextSize();
+        // If there is a max text size set, use the lesser of that and the default text size
+        float targetTextSize = mMaxTextSize > 0 ? Math.min(mTextSize, mMaxTextSize) : mTextSize;
+
+        // Get the required text height
+        int textHeight = getTextHeight(text, textPaint, width, targetTextSize);
+
+        // Until we either fit within our text view or we had reached our min text size, incrementally try smaller sizes
+        while (textHeight > height && targetTextSize > mMinTextSize) {
+            targetTextSize = Math.max(targetTextSize - 2, mMinTextSize);
+            textHeight = getTextHeight(text, textPaint, width, targetTextSize);
+        }
+
+        // If we had reached our minimum text size and still don't fit, append an ellipsis
+        if (mAddEllipsis && targetTextSize == mMinTextSize && textHeight > height) {
+            // Draw using a static layout
+            // modified: use a copy of TextPaint for measuring
+            TextPaint paint = new TextPaint(textPaint);
+            // Draw using a static layout
+            StaticLayout layout = new StaticLayout(text, paint, width, Layout.Alignment.ALIGN_NORMAL,
+                    mSpacingMult, mSpacingAdd, false);
+            // Check that we have a least one line of rendered text
+            if (layout.getLineCount() > 0) {
+                // Since the line at the specific vertical position would be cut off,
+                // we must trim up to the previous line
+                int lastLine = layout.getLineForVertical(height) - 1;
+                // If the text would not even fit on a single line, clear it
+                if (lastLine < 0) {
+                    setText("");
+                } else {
+                    // Otherwise, trim to the previous line and add an ellipsis
+                    int start = layout.getLineStart(lastLine);
+                    int end = layout.getLineEnd(lastLine);
+                    float lineWidth = layout.getLineWidth(lastLine);
+                    float ellipseWidth = paint.measureText(M_ELLIPSIS);
+
+                    // Trim characters off until we have enough room to draw the ellipsis
+                    while (width < lineWidth + ellipseWidth) {
+                        lineWidth = paint.measureText(text.subSequence(start, --end + 1).toString());
+                    }
+                    setText(text.subSequence(0, end) + M_ELLIPSIS);
+                }
+            }
+        }
+
+        // Some devices try to auto adjust line spacing, so force default line spacing
+        // and invalidate the layout as a side effect
+        setTextSize(TypedValue.COMPLEX_UNIT_PX, targetTextSize);
+        setLineSpacing(mSpacingAdd, mSpacingMult);
+
+        // Notify the listener if registered
+        if (mTextResizeListener != null) {
+            mTextResizeListener.onTextResize(this, oldTextSize, targetTextSize);
+        }
+
+        // Reset force resize flag
+        mNeedsResize = false;
+    }
+
+    // Set the text size of the text paint object and use a static layout to render text off screen before measuring
+    private int getTextHeight(CharSequence source, TextPaint paint, int width, float textSize) {
+        // modified: make a copy of the original TextPaint object for measuring
+        // (apparently the object gets modified while measuring, see also the
+        // docs for TextView.getPaint() (which states to access it read-only)
+        TextPaint paintCopy = new TextPaint(paint);
+        // Update the text paint object
+        paintCopy.setTextSize(textSize);
+        // Measure using a static layout
+        StaticLayout layout = new StaticLayout(source, paintCopy, width, Layout.Alignment.ALIGN_NORMAL,
+                mSpacingMult, mSpacingAdd, true);
+        return layout.getHeight();
+    }
+}