Android Open Source - GuiLib Text Drawer

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License

The source code is released under:

Apache License

Java Source Code

/*
 * Copyright 2014 Alex Curran//from  w ww  .j a  va2  s.c  o  m
 *
 * 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.github.amlcurran.showcaseview;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.text.DynamicLayout;
import android.text.Layout;
import android.text.SpannableString;
import android.text.TextPaint;
import android.text.TextUtils;
import android.text.style.TextAppearanceSpan;

import com.gandulf.guilib.R;

/**
 * Draws the text as required by the ShowcaseView
 */
class TextDrawer {

  private final TextPaint titlePaint;
  private final TextPaint textPaint;
  private final Context context;
  private final ShowcaseAreaCalculator calculator;
  private final float padding;
  private final float actionBarOffset;

  private CharSequence mTitle, mDetails;
  private float[] mBestTextPosition = new float[3];
  private DynamicLayout mDynamicTitleLayout;
  private DynamicLayout mDynamicDetailLayout;
  private TextAppearanceSpan mTitleSpan;
  private TextAppearanceSpan mDetailSpan;
  private boolean hasRecalculated;

  public TextDrawer(Resources resources, ShowcaseAreaCalculator calculator, Context context) {
    padding = resources.getDimension(R.dimen.text_padding);
    actionBarOffset = resources.getDimension(R.dimen.action_bar_offset);

    this.calculator = calculator;
    this.context = context;

    titlePaint = new TextPaint();
    titlePaint.setAntiAlias(true);

    textPaint = new TextPaint();
    textPaint.setAntiAlias(true);
  }

  public void draw(Canvas canvas) {
    if (shouldDrawText()) {
      float[] textPosition = getBestTextPosition();

      if (!TextUtils.isEmpty(mTitle)) {
        canvas.save();
        if (hasRecalculated) {
          mDynamicTitleLayout = new DynamicLayout(mTitle, titlePaint, (int) textPosition[2],
              Layout.Alignment.ALIGN_NORMAL, 1.0f, 1.0f, true);
        }
        if (mDynamicTitleLayout != null) {
          canvas.translate(textPosition[0], textPosition[1]);
          mDynamicTitleLayout.draw(canvas);
          canvas.restore();
        }
      }

      if (!TextUtils.isEmpty(mDetails)) {
        canvas.save();
        if (hasRecalculated) {
          mDynamicDetailLayout = new DynamicLayout(mDetails, textPaint, (int) textPosition[2],
              Layout.Alignment.ALIGN_NORMAL, 1.2f, 1.0f, true);
        }
        float offsetForTitle = mDynamicTitleLayout != null ? mDynamicTitleLayout.getHeight() : 0;
        if (mDynamicDetailLayout != null) {
          canvas.translate(textPosition[0], textPosition[1] + offsetForTitle);
          mDynamicDetailLayout.draw(canvas);
          canvas.restore();
        }

      }
    }
    hasRecalculated = false;
  }

  public void setContentText(CharSequence details) {
    if (details != null) {
      SpannableString ssbDetail = new SpannableString(details);
      ssbDetail.setSpan(mDetailSpan, 0, ssbDetail.length(), 0);
      mDetails = ssbDetail;
    }
  }

  public void setContentTitle(CharSequence title) {
    if (title != null) {
      SpannableString ssbTitle = new SpannableString(title);
      ssbTitle.setSpan(mTitleSpan, 0, ssbTitle.length(), 0);
      mTitle = ssbTitle;
    }
  }

  /**
   * Calculates the best place to position text
   * 
   * @param canvasW
   *            width of the screen
   * @param canvasH
   *            height of the screen
   * @param shouldCentreText
   */
  public void calculateTextPosition(int canvasW, int canvasH, ShowcaseView showcaseView, boolean shouldCentreText) {

    Rect showcase = showcaseView.hasShowcaseView() ? calculator.getShowcaseRect() : new Rect();

    int[] areas = new int[4]; // left, top, right, bottom
    areas[0] = showcase.left * canvasH;
    areas[1] = showcase.top * canvasW;
    areas[2] = (canvasW - showcase.right) * canvasH;
    areas[3] = (canvasH - showcase.bottom) * canvasW;

    int largest = 0;
    for (int i = 1; i < areas.length; i++) {
      if (areas[i] > areas[largest])
        largest = i;
    }

    // Position text in largest area
    switch (largest) {
    case 0:
      mBestTextPosition[0] = padding;
      mBestTextPosition[1] = padding;
      mBestTextPosition[2] = showcase.left - 2 * padding;
      break;
    case 1:
      mBestTextPosition[0] = padding;
      mBestTextPosition[1] = padding + actionBarOffset;
      mBestTextPosition[2] = canvasW - 2 * padding;
      break;
    case 2:
      mBestTextPosition[0] = showcase.right + padding;
      mBestTextPosition[1] = padding;
      mBestTextPosition[2] = (canvasW - showcase.right) - 2 * padding;
      break;
    case 3:
      mBestTextPosition[0] = padding;
      mBestTextPosition[1] = showcase.bottom + padding;
      mBestTextPosition[2] = canvasW - 2 * padding;
      break;
    }
    if (shouldCentreText) {
      // Center text vertically or horizontally
      switch (largest) {
      case 0:
      case 2:
        mBestTextPosition[1] += canvasH / 4;
        break;
      case 1:
      case 3:
        mBestTextPosition[2] /= 2;
        mBestTextPosition[0] += canvasW / 4;
        break;
      }
    } else {
      // As text is not centered add actionbar padding if the text is left or right
      switch (largest) {
      case 0:
      case 2:
        mBestTextPosition[1] += actionBarOffset;
        break;
      }
    }

    hasRecalculated = true;
  }

  public void setTitleStyling(int styleId) {
    mTitleSpan = new TextAppearanceSpan(this.context, styleId);
    setContentTitle(mTitle);
  }

  public void setDetailStyling(int styleId) {
    mDetailSpan = new TextAppearanceSpan(this.context, styleId);
    setContentText(mDetails);
  }

  public CharSequence getContentTitle() {
    return mTitle;
  }

  public CharSequence getContentText() {
    return mDetails;
  }

  public float[] getBestTextPosition() {
    return mBestTextPosition;
  }

  public boolean shouldDrawText() {
    return !TextUtils.isEmpty(mTitle) || !TextUtils.isEmpty(mDetails);
  }
}

Java Source Code List

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