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Commit 80018c88 authored by Hans Boehm's avatar Hans Boehm
Browse files

Properly reserve display space for non-digits 

Bug: 22882700

We did not correctly calculate the extra space we might need to add
a decimal point to a scientific notation results.  We also
incorrectly assumed that minus signs are the same width as a
digit. As a workaround we now reserve extra space for the possible
non-digit characters to ensure that a result is never inadvertently
truncated.

Change-Id: I79b499121703cd51bbbf3e1d85b2285a2dd5e025
parent 9fd976e4

src/com/android/calculator2/CalculatorResult.java

+21 −7
Original line number Diff line number Diff line
@@ -102,7 +102,9 @@ public class CalculatorResult extends AlignedTextView { 
                            // we switch to scientific notation with positive exponent.

    private static final int SCI_NOTATION_EXTRA = 1;

                            // Extra digits for standard scientific notation.  In this case we

                            // have a deecimal point and no ellipsis.

                            // have a decimal point and no ellipsis.

                            // We assume that we do not drop digits to make room for the decimal

                            // point in ordinary scientific notation. Thus >= 1.

    private ActionMode mActionMode;

    private final ForegroundColorSpan mExponentColorSpan;
@@ -180,10 +182,24 @@ public class CalculatorResult extends AlignedTextView { 
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);



        final TextPaint paint = getPaint();

        final int newWidthConstraint = MeasureSpec.getSize(widthMeasureSpec)

                - (getPaddingLeft() + getPaddingRight())

                - (int) Math.ceil(Layout.getDesiredWidth(KeyMaps.ELLIPSIS, paint));

        final Context context = getContext();

        final float newCharWidth = Layout.getDesiredWidth("\u2007", paint);

        // Digits are presumed to have no more than newCharWidth.

        // We sometimes replace a character by an ellipsis or, due to SCI_NOTATION_EXTRA, add

        // an extra decimal separator beyond the maximum number of characters we normally allow.

        // Empirically, our minus sign is also slightly wider than a digit, so we have to

        // account for that.  We never have both an ellipsis and two minus signs, and

        // we assume an ellipsis is no narrower than a minus sign.

        final float decimalSeparatorWidth = Layout.getDesiredWidth(

                context.getString(R.string.dec_point), paint);

        final float minusExtraWidth = Layout.getDesiredWidth(

                context.getString(R.string.op_sub), paint) - newCharWidth;

        final float ellipsisExtraWidth = Layout.getDesiredWidth(KeyMaps.ELLIPSIS, paint)

                - newCharWidth;

        final int extraWidth = (int) (Math.ceil(Math.max(decimalSeparatorWidth + minusExtraWidth,

                ellipsisExtraWidth)) + Math.max(minusExtraWidth, 0.0f));

        final int newWidthConstraint = MeasureSpec.getSize(widthMeasureSpec)

                - (getPaddingLeft() + getPaddingRight()) - extraWidth;

        synchronized(mWidthLock) {

            mWidthConstraint = newWidthConstraint;

            mCharWidth = newCharWidth;
@@ -474,9 +490,7 @@ public class CalculatorResult extends AlignedTextView { 
            // Return something conservatively big, to force sufficient evaluation.

            return MAX_WIDTH;

        } else {

            // Always allow for the ellipsis character which already accounted for in the width

            // constraint.

            return result + 1;

            return result;

        }

    }