Java tutorial
package org.wikipedia.page.shareafact; import android.content.Context; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.LinearGradient; import android.graphics.Paint; import android.graphics.Rect; import android.graphics.Shader; import android.graphics.Typeface; import android.graphics.drawable.Drawable; import android.os.Build; import android.support.annotation.NonNull; import android.support.annotation.Nullable; import android.support.v4.content.ContextCompat; import android.support.v4.graphics.drawable.DrawableCompat; import android.text.Layout; import android.text.Spanned; import android.text.StaticLayout; import android.text.TextPaint; import android.text.TextUtils; import org.wikipedia.R; import org.wikipedia.gallery.ImageLicense; import org.wikipedia.util.L10nUtil; import org.wikipedia.util.StringUtil; import static android.text.Layout.Alignment.ALIGN_NORMAL; import static android.text.Layout.Alignment.ALIGN_OPPOSITE; /** * Creator and holder of a Bitmap which is comprised of an optional lead image, a title, * optional description, text, the Wikipedia wordmark, and some license icons. * * Creates a device-independent bitmap object; all dimension values are in px, not dp. */ public final class SnippetImage { private static final int WIDTH = 640; private static final int HEIGHT = 360; private static final int BOTTOM_PADDING = 25; private static final int HORIZONTAL_PADDING = 30; private static final int TOP_PADDING = 22; private static final int TEXT_WIDTH = WIDTH - 2 * HORIZONTAL_PADDING; private static final int DESCRIPTION_WIDTH = 360; private static final int ICONS_WIDTH = 16; private static final int ICONS_HEIGHT = 16; private static final float SPACING_MULTIPLIER = 1.0f; private static final Typeface SERIF = Typeface.create("serif", Typeface.NORMAL); private static final int QUARTER = 4; /** * Creates a card image usable for sharing and the preview of the same. * If we have a leadImageBitmap the use that as the background. If not then * just use a black background. */ public static Bitmap getSnippetImage(@NonNull Context context, @Nullable Bitmap leadImageBitmap, @NonNull String title, @Nullable String description, @NonNull CharSequence textSnippet, @NonNull ImageLicense license) { Bitmap resultBitmap = drawBackground(leadImageBitmap, license); Canvas canvas = new Canvas(resultBitmap); if (leadImageBitmap != null) { drawGradient(canvas); } Layout textLayout = drawTextSnippet(canvas, textSnippet); boolean isArticleRTL = textLayout.getParagraphDirection(0) == Layout.DIR_RIGHT_TO_LEFT; drawLicenseIcons(context, leadImageBitmap, license, canvas, isArticleRTL); int top = drawDescription(canvas, description, HEIGHT - BOTTOM_PADDING - ICONS_HEIGHT, isArticleRTL); drawTitle(canvas, title, top, isArticleRTL); if (L10nUtil.canLangUseImageForWikipediaWordmark(context)) { drawWordmarkFromStaticImage(context, canvas, isArticleRTL); } else { drawWordmarkFromText(context, canvas, isArticleRTL); } return resultBitmap; } @NonNull private static Bitmap drawBackground(@Nullable Bitmap leadImageBitmap, @NonNull ImageLicense license) { Bitmap resultBitmap; if (leadImageBitmap != null && license.hasLicenseInfo()) { // use lead image resultBitmap = scaleCropToFit(leadImageBitmap, WIDTH, HEIGHT); } else { resultBitmap = Bitmap.createBitmap(WIDTH, HEIGHT, Bitmap.Config.ARGB_8888); final int backgroundColor = 0xff242438; resultBitmap.eraseColor(backgroundColor); } return resultBitmap; } private static void drawGradient(@NonNull Canvas canvas) { // draw a dark gradient over the image, so that the white text // will stand out better against it. final int gradientStartColor = 0x60000000; final int gradientStopColor = 0xA0000000; Shader shader = new LinearGradient(0, 0, 0, canvas.getHeight(), gradientStartColor, gradientStopColor, Shader.TileMode.CLAMP); Paint paint = new Paint(); paint.setShader(shader); canvas.drawRect(new Rect(0, 0, canvas.getWidth(), canvas.getHeight()), paint); } @NonNull private static Layout drawTextSnippet(@NonNull Canvas canvas, @NonNull CharSequence textSnippet) { final int top = TOP_PADDING; final int maxHeight = 225; final int maxLines = 5; final float maxFontSize = 195.0f; final float minFontSize = 32.0f; TextPaint textPaint = new TextPaint(); textPaint.setAntiAlias(true); textPaint.setColor(Color.WHITE); textPaint.setTextSize(maxFontSize); textPaint.setStyle(Paint.Style.FILL); textPaint.setTypeface(Typeface.DEFAULT_BOLD); textPaint.setShadowLayer(1.0f, 1.0f, 1.0f, Color.GRAY); StaticLayout textLayout = optimizeTextSize( new TextLayoutParams(textSnippet, textPaint, TEXT_WIDTH, SPACING_MULTIPLIER), maxHeight, maxLines, maxFontSize, minFontSize); canvas.save(); int horizontalCenterOffset = top + (maxHeight - textLayout.getHeight()) / QUARTER; canvas.translate(HORIZONTAL_PADDING, horizontalCenterOffset); textLayout.draw(canvas); canvas.restore(); return textLayout; } private static int drawDescription(@NonNull Canvas canvas, @Nullable String description, int top, boolean isArticleRTL) { final int marginBottom = 5; final int maxHeight = 23; final int maxLines = 2; final float maxFontSize = 15.0f; final float minFontSize = 10.0f; if (TextUtils.isEmpty(description)) { return top - marginBottom; } TextPaint textPaint = new TextPaint(); textPaint.setAntiAlias(true); textPaint.setColor(Color.WHITE); textPaint.setTextSize(maxFontSize); textPaint.setStyle(Paint.Style.FILL); textPaint.setShadowLayer(1.0f, 0.0f, 0.0f, Color.GRAY); StaticLayout textLayout = optimizeTextSize( new TextLayoutParams(description, textPaint, DESCRIPTION_WIDTH, SPACING_MULTIPLIER), maxHeight, maxLines, maxFontSize, minFontSize); int left = HORIZONTAL_PADDING; if (isArticleRTL) { left = WIDTH - HORIZONTAL_PADDING - textLayout.getWidth(); } top = top - marginBottom - textLayout.getHeight(); canvas.save(); canvas.translate(left, top); textLayout.draw(canvas); canvas.restore(); return top; } private static void drawTitle(@NonNull Canvas canvas, @NonNull String title, int top, boolean isArticleRTL) { final int marginBottom = 0; final int maxHeight = 70; final int maxLines = 2; final float maxFontSize = 30.0f; final float spacingMultiplier = 0.7f; TextPaint textPaint = new TextPaint(); textPaint.setAntiAlias(true); textPaint.setColor(Color.WHITE); textPaint.setTextSize(maxFontSize); textPaint.setStyle(Paint.Style.FILL); textPaint.setTypeface(SERIF); textPaint.setShadowLayer(1.0f, 0.0f, 1.0f, Color.GRAY); StaticLayout textLayout = optimizeTextSize( new TextLayoutParams(title, textPaint, DESCRIPTION_WIDTH, spacingMultiplier), maxHeight, maxLines, maxFontSize, maxFontSize); int left = HORIZONTAL_PADDING; if (isArticleRTL) { left = WIDTH - HORIZONTAL_PADDING - textLayout.getWidth(); } int marginBottomTotal = marginBottom; if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) { // versions < 5.0 don't compensate for bottom margin correctly when line // spacing is less than 1.0, so we'll compensate ourselves final int marginBoost = 10; marginBottomTotal += marginBoost; } top = top - marginBottomTotal - textLayout.getHeight(); canvas.save(); canvas.translate(left, top); textLayout.draw(canvas); canvas.restore(); } private static void drawLicenseIcons(@NonNull Context context, @Nullable Bitmap leadImageBitmap, @NonNull ImageLicense license, @NonNull Canvas canvas, boolean isArticleRTL) { final int bottom = SnippetImage.HEIGHT - SnippetImage.BOTTOM_PADDING; final int top = bottom - SnippetImage.ICONS_HEIGHT; int left = SnippetImage.HORIZONTAL_PADDING; int right = left + SnippetImage.ICONS_WIDTH; if (isArticleRTL) { right = SnippetImage.WIDTH - SnippetImage.HORIZONTAL_PADDING; left = right - SnippetImage.ICONS_WIDTH; } Drawable d = ContextCompat.getDrawable(context, shouldDefaultToCCLicense(leadImageBitmap, license) ? R.drawable.ic_license_cc : license.getLicenseIcon()); d.setBounds(left, top, right, bottom); d.draw(canvas); } /** * Default to showing Creative Commons license icon for card as a whole if lead image is not present * or will not be used due to a lack of licensing data. */ private static boolean shouldDefaultToCCLicense(@Nullable Bitmap leadImageBitmap, @NonNull ImageLicense license) { return leadImageBitmap == null || !license.hasLicenseInfo(); } private static void drawWordmarkFromStaticImage(@NonNull Context context, @NonNull Canvas canvas, boolean isArticleRTL) { // scaling it a bit down from original 317x54px size final int width = 130; final int height = 22; final int bottom = HEIGHT - BOTTOM_PADDING; final int top = bottom - height; Drawable d = ContextCompat.getDrawable(context, R.drawable.wp_wordmark); DrawableCompat.setTint(d, Color.LTGRAY); int left = WIDTH - HORIZONTAL_PADDING - width; if (isArticleRTL) { left = HORIZONTAL_PADDING; } int right = left + width; d.setBounds(left, top, right, bottom); d.draw(canvas); } private static void drawWordmarkFromText(@NonNull Context context, @NonNull Canvas canvas, boolean isArticleRTL) { final int maxWidth = WIDTH - DESCRIPTION_WIDTH - 2 * HORIZONTAL_PADDING; final float fontSize = 20.0f; final float scaleX = 1.06f; TextPaint textPaint = new TextPaint(); textPaint.setAntiAlias(true); textPaint.setColor(Color.LTGRAY); textPaint.setTextSize(fontSize); textPaint.setTypeface(SERIF); textPaint.setTextScaleX(scaleX); Spanned wikipedia = StringUtil.fromHtml(context.getString(R.string.wp_stylized)); Layout.Alignment align = L10nUtil.isDeviceRTL() ? ALIGN_OPPOSITE : ALIGN_NORMAL; StaticLayout wordmarkLayout = buildLayout( new TextLayoutParams(wikipedia, textPaint, maxWidth, 1.0f, align)); final int width = (int) wordmarkLayout.getLineWidth(0); final int height = wordmarkLayout.getHeight(); final int bottom = HEIGHT - BOTTOM_PADDING; final int top = bottom - height; int left = WIDTH - HORIZONTAL_PADDING - width; if (isArticleRTL) { left = HORIZONTAL_PADDING; } canvas.save(); // -- canvas.translate(left, top); wordmarkLayout.draw(canvas); canvas.restore(); // -- } /** * If the title or text is too long we first reduce the font size. * If that is not enough it gets ellipsized. */ private static StaticLayout optimizeTextSize(TextLayoutParams params, int maxHeight, int maxLines, float maxFontSize, float minFontSize) { final float threshold1 = 60.0f; final float threshold2 = 40.0f; final float extraStep1 = 3.0f; final float extraStep2 = 1.0f; boolean fits = false; StaticLayout textLayout = null; // Try decreasing font size first for (float fontSize = maxFontSize; fontSize >= minFontSize; fontSize -= 1.0f) { params.textPaint.setTextSize(fontSize); textLayout = buildLayout(params); if (textLayout.getHeight() <= maxHeight) { fits = true; break; } // make it go faster at the beginning... if (fontSize > threshold1) { fontSize -= extraStep1; } else if (fontSize > threshold2) { fontSize -= extraStep2; } } // Then do own ellipsize: cut text off after last fitting space and add "..." // Didn't want to cut off randomly in the middle of a line or word. if (!fits) { final String textStr = params.text.toString(); final int ellipsisLength = 3; final int ellipsisStart = textLayout != null ? textLayout.getLineStart(maxLines) - ellipsisLength : textStr.length(); final int end = textStr.lastIndexOf(' ', ellipsisStart) + 1; if (end > 0) { textLayout = buildLayout(new TextLayoutParams(params, textStr.substring(0, end) + "...")); if (textLayout.getLineCount() <= maxLines) { fits = true; } } } // last resort: use TextUtils.ellipsize() if (!fits) { final float textRatio = .87f; final float maxWidth = textRatio * maxLines * params.lineWidth; textLayout = buildLayout(new TextLayoutParams(params, TextUtils.ellipsize(params.text, params.textPaint, maxWidth, TextUtils.TruncateAt.END))); } return textLayout; } private static StaticLayout buildLayout(TextLayoutParams params) { return new StaticLayout(params.text, params.textPaint, params.lineWidth, params.align, params.spacingMultiplier, 0.0f, false); } // Borrowed from http://stackoverflow.com/questions/5226922/crop-to-fit-image-in-android // Modified to allow for face detection adjustment, startY @NonNull private static Bitmap scaleCropToFit(@NonNull Bitmap original, int targetWidth, int targetHeight) { // Need to scale the image, keeping the aspect ratio first int width = original.getWidth(); int height = original.getHeight(); float widthScale = (float) targetWidth / (float) width; float heightScale = (float) targetHeight / (float) height; float scaledWidth; float scaledHeight; int startX = 0; int startY = 0; if (widthScale > heightScale) { scaledWidth = targetWidth; scaledHeight = height * widthScale; startY = (int) (scaledHeight - targetHeight) / 2; if (startY < 0) { startY = 0; } else if (startY + targetHeight > scaledHeight) { startY = (int) (scaledHeight - targetHeight); } } else { scaledHeight = targetHeight; scaledWidth = width * heightScale; } Bitmap scaledBitmap = Bitmap.createScaledBitmap(original, (int) scaledWidth, (int) scaledHeight, true); Bitmap bitmap = Bitmap.createBitmap(scaledBitmap, startX, startY, targetWidth, targetHeight); scaledBitmap.recycle(); return bitmap; } /** * Parameter object for #buildLayout and #optimizeTextSize. */ private static class TextLayoutParams { private final CharSequence text; private final TextPaint textPaint; private final int lineWidth; private final float spacingMultiplier; private final Layout.Alignment align; /** Copy constructor with updated text */ TextLayoutParams(TextLayoutParams other, CharSequence text) { this.text = text; this.textPaint = other.textPaint; this.lineWidth = other.lineWidth; this.spacingMultiplier = other.spacingMultiplier; this.align = other.align; } TextLayoutParams(CharSequence text, TextPaint textPaint, int lineWidth, float spacingMultiplier, Layout.Alignment align) { this.text = text; this.textPaint = textPaint; this.lineWidth = lineWidth; this.spacingMultiplier = spacingMultiplier; this.align = align; } private TextLayoutParams(CharSequence text, TextPaint textPaint, int lineWidth, float spacingMultiplier) { this(text, textPaint, lineWidth, spacingMultiplier, ALIGN_NORMAL); } } private SnippetImage() { } }