Restructure display formatting, use TextView for formula.

This fixes issues with inappropriate keyboard popups and cleans
up the code.

This substantially rewrites the result formatting code;
it intentionally removes a heuristic to avoid conventional scientific
notation for short results, which only seemed to confuse things.
There are some other tweaks and simplifications.  Transitions
to and from conventional scientific notation should be smoother,
though there is still an issue with numbers like 10^-30.
The formatting code is completely extracted from Evaluator, cutting
off various tentacles, and moved to CalculatorResult.

Fixes a bug that resulted in digits being inappropriately
displayed without an exponent if the decimal point was just off
the left edge of the screen.

It's still not clear that we should always be integrating the
exponent into the result window.

Bug: 20483801
Bug: 20480081

Change-Id: I1bb777b871e9fa8b6cd510c533e4b94bde6d4a20

1 files changed, 240 insertions, 0 deletions

diff --git a/src/com/android/calculator2/CalculatorText.java b/src/com/android/calculator2/CalculatorText.java
new file mode 100644
index 0000000..01f234b
--- /dev/null
+++ b/src/com/android/calculator2/CalculatorText.java
@@ -0,0 +1,240 @@
+/*
+ * Copyright (C) 2014 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
+ *
+ *   http://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.android.calculator2;
+
+import android.content.ClipboardManager;
+import android.content.ClipData;
+import android.content.Context;
+import android.content.res.TypedArray;
+import android.graphics.Paint;
+import android.graphics.Paint.FontMetricsInt;
+import android.graphics.Rect;
+import android.net.Uri;
+import android.os.Parcelable;
+import android.text.method.ScrollingMovementMethod;
+import android.text.TextPaint;
+import android.util.AttributeSet;
+import android.util.Log;
+import android.util.TypedValue;
+import android.view.ActionMode;
+import android.view.GestureDetector;
+import android.view.Menu;
+import android.view.MenuInflater;
+import android.view.MenuItem;
+import android.view.MotionEvent;
+import android.view.View;
+import android.widget.TextView;
+
+/**
+ * TextView adapted for Calculator display.
+ */
+
+public class CalculatorText extends TextView implements View.OnLongClickListener{
+
+
+    private final ActionMode.Callback mPasteActionModeCallback =
+            new ActionMode.Callback() {
+        @Override
+        public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
+            switch (item.getItemId()) {
+            case R.id.menu_paste:
+                pasteContent();
+                mode.finish();
+                return true;
+            default:
+                return false;
+            }
+        }
+
+        @Override
+        public boolean onCreateActionMode(ActionMode mode, Menu menu) {
+            ClipboardManager clipboard =
+                (ClipboardManager) getContext().getSystemService(
+                        Context.CLIPBOARD_SERVICE);
+            if (clipboard.hasPrimaryClip()) {
+                MenuInflater inflater = mode.getMenuInflater();
+                inflater.inflate(R.menu.paste, menu);
+                return true;
+            }
+            // Prevents the selection action mode on double tap.
+            return false;
+        }
+
+        @Override
+        public void onDestroyActionMode(ActionMode mode) {
+        }
+
+        @Override
+        public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
+            return false;
+        }
+    };
+
+    private PasteListener mPasteListener;
+
+    public void setPasteListener(PasteListener pasteListener) {
+        mPasteListener = pasteListener;
+    }
+
+    private void pasteContent() {
+        ClipboardManager clipboard =
+                (ClipboardManager) getContext().getSystemService(
+                        Context.CLIPBOARD_SERVICE);
+        ClipData cd = clipboard.getPrimaryClip();
+        ClipData.Item item = cd.getItemAt(0);
+        // TODO: Should we handle multiple selections?
+        Uri uri = item.getUri();
+        if (uri == null || !mPasteListener.paste(uri)) {
+            mPasteListener.paste(item.coerceToText(getContext()).toString());
+        }
+    }
+
+    private final float mMaximumTextSize;
+    private final float mMinimumTextSize;
+    private final float mStepTextSize;
+
+    // Temporary objects for use in layout methods.
+    private final Paint mTempPaint = new TextPaint();
+    private final Rect mTempRect = new Rect();
+
+    private int mWidthConstraint = -1;
+    private OnTextSizeChangeListener mOnTextSizeChangeListener;
+
+    public CalculatorText(Context context) {
+        this(context, null);
+    }
+
+    public CalculatorText(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    public CalculatorText(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+
+        final TypedArray a = context.obtainStyledAttributes(
+                attrs, R.styleable.CalculatorText, defStyle, 0);
+        mMaximumTextSize = a.getDimension(
+                R.styleable.CalculatorText_maxTextSize, getTextSize());
+        mMinimumTextSize = a.getDimension(
+                R.styleable.CalculatorText_minTextSize, getTextSize());
+        mStepTextSize = a.getDimension(R.styleable.CalculatorText_stepTextSize,
+                (mMaximumTextSize - mMinimumTextSize) / 3);
+
+        a.recycle();
+
+        // Paste ActionMode is triggered explicitly, not through
+        // setCustomSelectionActionModeCallback.
+        setOnLongClickListener(this);
+
+        // Enable scrolling
+        setMovementMethod(ScrollingMovementMethod.getInstance());
+
+        setTextSize(TypedValue.COMPLEX_UNIT_PX, mMaximumTextSize);
+        setMinHeight(getLineHeight() + getCompoundPaddingBottom() + getCompoundPaddingTop());
+    }
+
+    @Override
+    public boolean onLongClick(View v) {
+        startActionMode(mPasteActionModeCallback);
+        return true;
+    }
+
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
+
+        mWidthConstraint =
+                MeasureSpec.getSize(widthMeasureSpec) - getPaddingLeft() - getPaddingRight();
+        setTextSize(TypedValue.COMPLEX_UNIT_PX, getVariableTextSize(getText().toString()));
+    }
+
+    public int getWidthConstraint() { return mWidthConstraint; }
+
+    @Override
+    protected void onTextChanged(CharSequence text, int start, int lengthBefore, int lengthAfter) {
+        super.onTextChanged(text, start, lengthBefore, lengthAfter);
+
+        final int textLength = text.length();
+        setTextSize(TypedValue.COMPLEX_UNIT_PX, getVariableTextSize(text.toString()));
+    }
+
+    @Override
+    public void setTextSize(int unit, float size) {
+        final float oldTextSize = getTextSize();
+        super.setTextSize(unit, size);
+
+        if (mOnTextSizeChangeListener != null && getTextSize() != oldTextSize) {
+            mOnTextSizeChangeListener.onTextSizeChanged(this, oldTextSize);
+        }
+    }
+
+    public void setOnTextSizeChangeListener(OnTextSizeChangeListener listener) {
+        mOnTextSizeChangeListener = listener;
+    }
+
+    public float getVariableTextSize(String text) {
+        if (mWidthConstraint < 0 || mMaximumTextSize <= mMinimumTextSize) {
+            // Not measured, bail early.
+            return getTextSize();
+        }
+
+        // Capture current paint state.
+        mTempPaint.set(getPaint());
+
+        // Step through increasing text sizes until the text would no longer fit.
+        float lastFitTextSize = mMinimumTextSize;
+        while (lastFitTextSize < mMaximumTextSize) {
+            final float nextSize = Math.min(lastFitTextSize + mStepTextSize, mMaximumTextSize);
+            mTempPaint.setTextSize(nextSize);
+            if (mTempPaint.measureText(text) > mWidthConstraint) {
+                break;
+            } else {
+                lastFitTextSize = nextSize;
+            }
+        }
+
+        return lastFitTextSize;
+    }
+
+    @Override
+    public int getCompoundPaddingTop() {
+        // Measure the top padding from the capital letter height of the text instead of the top,
+        // but don't remove more than the available top padding otherwise clipping may occur.
+        getPaint().getTextBounds("H", 0, 1, mTempRect);
+
+        final FontMetricsInt fontMetrics = getPaint().getFontMetricsInt();
+        final int paddingOffset = -(fontMetrics.ascent + mTempRect.height());
+        return super.getCompoundPaddingTop() - Math.min(getPaddingTop(), paddingOffset);
+    }
+
+    @Override
+    public int getCompoundPaddingBottom() {
+        // Measure the bottom padding from the baseline of the text instead of the bottom, but don't
+        // remove more than the available bottom padding otherwise clipping may occur.
+        final FontMetricsInt fontMetrics = getPaint().getFontMetricsInt();
+        return super.getCompoundPaddingBottom() - Math.min(getPaddingBottom(), fontMetrics.descent);
+    }
+
+    public interface OnTextSizeChangeListener {
+        void onTextSizeChanged(TextView textView, float oldSize);
+    }
+
+    public interface PasteListener {
+        void paste(String s);
+        boolean paste(Uri u);
+    }
+}