Develop Reference

Android imageView with checkeredBackground and different size images ontop

Background
I have an ImageView which is used to display previews of a file.
I would like to have the ImageView with a checkerboard background, so that when a file with transparency is rendered on top (such as PNG and SVG files) the checkerboard shows through on the transparent parts.
I have found lots of questions on StackOverflow on how to create the checkered background and this question is not entirely specific to that.
I am currently doing it in code. I create a 2 by 2 bitmap (top left/bottom right are one colour, top right, bottom left are the other colour) where the size of each box is specified. Then i create the main bitmap by drawing this small bitmap repeatedly.
int checkeredBackgroundSquareSize= 16;
private static Bitmap getCheckeredBitmap(int size) {
size = (size > 0) ? size : DEFAULT_SQUARE_SIZE;
int colorOne = ContentApplication.appCtx().getColor(R.color.checkerboard_background_color_one);
int colorTwo = ContentApplication.appCtx().getColor(R.color.checkerboard_background_color_two);
// width/height is twice the size of the individual squares
Bitmap squareBitmap = Bitmap.createBitmap(size*2, size*2, Bitmap.Config.ARGB_8888);
Paint bitmapPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
bitmapPaint.setStyle(Paint.Style.FILL);
Canvas canvas = new Canvas(squareBitmap);
// draw 2 rectangles on 2 rows
// top left and bottom right are the first colour
// top right and bottom left are the second colour
// set colour for top left/bottom right squares
bitmapPaint.setColor(colorOne);
// Square 1 : top left
Rect rect = new Rect(0, 0, size, size);
canvas.drawRect(rect, bitmapPaint);
// Square 2 : bottom right
rect.offset(size, size);
canvas.drawRect(rect, bitmapPaint);
// change colour for top right/bottom left squares
bitmapPaint.setColor(colorTwo);
// Square 3 : top right
rect.offset(-size, 0);
canvas.drawRect(rect, bitmapPaint);
// Square 4: bottom left
rect.offset(size, -size);
canvas.drawRect(rect, bitmapPaint);
return squareBitmap;
}
I then create a Bitmap the size of my preview image, and use the checkered background bitmap to repeatedly draw on the canvas before the preview image is added on top.
// Create a Bitmap to render our SVG to
Bitmap bitmap = Bitmap.createBitmap(bitmapWidth, bitmapHeight, Bitmap.Config.ARGB_8888);
// Create a Canvas to use for rendering
Canvas canvas = new Canvas(bitmap);
// If we don't specify a viewport box, then AndroidSVG will use the bounds of the Canvas
// as the viewport. So a scale of 1.0 corresponds to that size
canvas.scale(scaling,scaling );
// create the checkered background, indicating transparency
Bitmap square = getCheckeredBitmap(checkeredBackgroundSquareSize);
BitmapShader shader = new BitmapShader(square, Shader.TileMode.REPEAT, Shader.TileMode.REPEAT);
Paint paint = new Paint();
paint.setShader(shader);
// in your draw method
canvas.drawRect(0, 0, bitmapWidth, bitmapHeight, paint);
The issue
My previews can be different sizes, for example 100x100, 6000x2000 etc As i am creating the initial bitmap on these sizes, the final image for the files all render looking like the squares on the checkered background are different sizes.
I need to have the checkerboard look exactly the same regardless of the overlaid image's size.
Is there a way to set a background image for an ImageView to be an image. I can only see how to set it to a drawable and I can not see how to define a checkboard as an xml drawable.

Mike M gave the answer that solved my issue. See Mike's comments to the first post
Create your own Drawable that renders the checkerboard
public class CheckerboardDrawable extends Drawable {
// I inadvertently ran the example image with Paint.ANTI_ALIAS_FLAG, but
// we actually don't want that 'cause we're looking for crisp, clean lines.
private final Paint paint = new Paint();
private int checkeredBackgroundSquareSize = 16;
private int colorOne = Color.LTGRAY;
private int colorTwo = Color.WHITE;
#Override
public void draw(#NonNull Canvas canvas) {
final Rect bounds = getBounds();
final int squareSize = checkeredBackgroundSquareSize;
final int columns = bounds.width() / squareSize + 1;
final int rows = bounds.height() / squareSize + 1;
canvas.translate(bounds.left, bounds.top);
for (int c = 0; c < columns; c++) {
for (int r = 0; r < rows; r++) {
paint.setColor((c + r) % 2 == 0 ? colorOne : colorTwo);
final int x = c * squareSize;
final int y = r * squareSize;
canvas.drawRect(x, y, x + squareSize, y + squareSize, paint);
}
}
canvas.translate(-bounds.left, -bounds.top);
}
#Override
public int getOpacity() {
return PixelFormat.TRANSLUCENT;
}
#Override
public void setAlpha(int alpha) {}
#Override
public void setColorFilter(#Nullable ColorFilter colorFilter) {}
}
Then add the drawable to the ImageView
final ImageView imageView = findViewById(R.id.image);
imageView.setBackground(new CheckerboardDrawable());

How to combine TextView and an image and return an image?

While searching for results I came across this
How can I convert a View to a Drawable?
The idea behind this is I can convert TextView into a bitmap first and then combine the two bitmaps. But by converting the TextView into Bitmap, it would make it lose it's transparency which I don't want. I want the TextView over my ImageView but as one image using canvas.
My idea is to create images like these:
Here I want to enclose the text with a drawable shape for that white border.
And then place this Textview on an image and then save everything as a bitmap.
Please help

You can try to draw text and lines on canvas.
Below is example method which draws text on drawable image and returns Bitmap.
You can set custom font by calling .setTypeface() on Paint object.
Call canvas.drawLine() to draw line. To customize your line you can create new Paint object, set its color and width by .setColor() and .setStrokeWidth() and pass it in drawLine() together with line coordinates.
public Bitmap drawTextOnBitmap(Context context, int resId, String text) {
// prepare canvas
Resources resources = context.getResources();
float scale = resources.getDisplayMetrics().density;
Bitmap bitmap = BitmapFactory.decodeResource(resources, resId);
android.graphics.Bitmap.Config bitmapConfig = bitmap.getConfig();
// set default bitmap config if none
if (bitmapConfig == null) {
bitmapConfig = android.graphics.Bitmap.Config.ARGB_8888;
}
// resource bitmaps are immutable, so we need to convert it to mutable one
bitmap = bitmap.copy(bitmapConfig, true);
Canvas canvas = new Canvas(bitmap);
// new antialiased Paint
TextPaint paint = new TextPaint(Paint.ANTI_ALIAS_FLAG);
// text color - #3D3D3D
paint.setColor(Color.rgb(61, 61, 61));
// text size in pixels
paint.setTextSize((int) (bitmap.getHeight() / 10 * scale));
// text shadow
paint.setShadowLayer(1f, 0f, 1f, Color.WHITE);
// set text width to canvas width minus 16dp padding
int textWidth = canvas.getWidth() - (int) (16 * scale);
// init StaticLayout for text
StaticLayout textLayout = new StaticLayout(text, paint, textWidth,
Layout.Alignment.ALIGN_CENTER, 1.0f, 0.0f, false);
// get height of multiline text
int textHeight = textLayout.getHeight();
// get position of text's top left corner
float x = (bitmap.getWidth() - textWidth) / 2;
float y = (bitmap.getHeight() - textHeight) / 2;
// draw text to the Canvas center
canvas.save();
canvas.translate(x, y);
textLayout.draw(canvas);
canvas.restore();
return bitmap;
}
Update:
To draw rectangle add this to the method:
Paint p = new Paint();
p.setStyle(Paint.Style.STROKE);
p.setStrokeWidth(24);
RectF rectF = new RectF(80, 150, 200, 350);
canvas.drawRect(rectF, p);
Parameters for new RectF():
left
The X coordinate of the left side of the rectangle
top
The Y coordinate of the top of the rectangle
right
The X coordinate of the right side of the rectangle
bottom
The Y coordinate of the bottom of the rectangle

Android Cover Flow with image shadow effect

I want to implement cover flow as below
I have tried Carousel, but its not the same thing. Did some google search was not able to find something even near to the cover flow implemented in given example.

Definitely have a look at this, FancyCoverFlow.
There is a demo app for it in the Play store as well that shows the reflection requirement you'd like.

have you tried this:
blog post
public Bitmap getRefelection(Bitmap image) {
// The gap we want between the reflection and the original image
final int reflectionGap = 0;
// Get you bit map from drawable folder
Bitmap originalImage = image;
int width = originalImage.getWidth();
int height = originalImage.getHeight();
// This will not scale but will flip on the Y axis
Matrix matrix = new Matrix();
matrix.preScale(1, -1);
// Create a Bitmap with the flip matix applied to it.
// We only want the bottom half of the image
/*if(bitmapWithReflection!=null && !bitmapWithReflection.isRecycled()){
bitmapWithReflection.recycle();
bitmapWithReflection=null;
}*/
Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0,
height / 2, width, height / 2, matrix, false);
// Create a new bitmap with same width but taller to fit reflection
Bitmap bitmapWithReflection = Bitmap.createBitmap(width,(height + height / 2), Config.ARGB_8888);
// Create a new Canvas with the bitmap that's big enough for
// the image plus gap plus reflection
Canvas canvas = new Canvas(bitmapWithReflection);
// Draw in the original image
canvas.drawBitmap(originalImage, 0, 0, null);
//Draw the reflection Image
canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
// Create a shader that is a linear gradient that covers the reflection
Paint paint = new Paint();
LinearGradient shader = new LinearGradient(0,
originalImage.getHeight(), 0, bitmapWithReflection.getHeight()
+ reflectionGap, 0x40ffffff, 0x00ffffff, TileMode.CLAMP);
// Set the paint to use this shader (linear gradient)
paint.setShader(shader);
// Set the Transfer mode to be porter duff and destination in
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
// Draw a rectangle using the paint with our linear gradient
canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()
+ reflectionGap, paint);
if(originalImage!=null && originalImage.isRecycled()){
originalImage.recycle();
originalImage=null;
}
if(reflectionImage!=null && reflectionImage.isRecycled()){
reflectionImage.recycle();
reflectionImage=null;
}
return bitmapWithReflection;
}

Have you gone through the Android Coverflow which is bit different form the Carousel which you want.

I made cover flow widget which is not dependent on gallery.
You can find it here. I will add some samples later.
http://applm.github.io/ma-components/

Android drawText including text wrapping

I am currently creating an image editor and am attempting to draw text on top of on image using canvas.drawText(). So far I have been successful in doing this but when the user enters text that is too long, the text just continues on one line out of the page and doesn't wrap itself to the width of the screen. How would I go about doing this? I have tried using a static layout but cannot seem to get it to work, has anyone got a tutorial to do this?
My function for drawing on a canvas using static layout:
public Bitmap createImage(float scr_x,float scr_y,String user_text){
Canvas canvas = new Canvas(image);
scr_x = 100;
scr_y = 100;
final TextPaint tp = new TextPaint(Color.WHITE);
canvas.save();
StaticLayout sl = new StaticLayout("" + user_text, tp, originalBitmap.getWidth(), Layout.Alignment.ALIGN_NORMAL, 1.0f, 0.0f, false);
sl.draw(canvas);
return image;
}
Okay, I've updated my code, but when I try to draw on the image nothing happens at all, I have no idea why either:
public Bitmap createImage(String user_text) {
// canvas object with bitmap image as constructor
Canvas canvas = new Canvas(image);
TextPaint tp = new TextPaint();
tp.setColor(Color.RED);
tp.setTextSize(50);
tp.setTextAlign(Align.CENTER);
tp.setAntiAlias(true);
StaticLayout sl = new StaticLayout("" + user_text, tp,
canvas.getWidth(), Layout.Alignment.ALIGN_NORMAL, 1, 0, false);
canvas.translate(100, 100);
sl.draw(canvas);
return image;
}
Is staticlayout not meant to be used to draw on canvas?

Yes, StaticLayout is what you're meant to use to draw multi-line text on a Canvas. Save yourself a world of pain and don't think about breaking text yourself -- you're on the right path.
I'm not sure about the bitmap problem, but your second code above worked just fine to draw text on a canvas for me.
Learn to use StaticLayout , then draw the Layout object onto a canvas using the Layout.draw() method.
References

public Bitmap drawMultilineTextToBitmap(Context gContext,
int gResId,
String gText) {
// prepare canvas
Resources resources = gContext.getResources();
float scale = resources.getDisplayMetrics().density;
Bitmap bitmap = BitmapFactory.decodeResource(resources, gResId);
android.graphics.Bitmap.Config bitmapConfig = bitmap.getConfig();
// set default bitmap config if none
if(bitmapConfig == null) {
bitmapConfig = android.graphics.Bitmap.Config.ARGB_8888;
}
// resource bitmaps are imutable,
// so we need to convert it to mutable one
bitmap = bitmap.copy(bitmapConfig, true);
Canvas canvas = new Canvas(bitmap);
// new antialiased Paint
TextPaint paint=new TextPaint(Paint.ANTI_ALIAS_FLAG);
// text color - #3D3D3D
paint.setColor(Color.rgb(61, 61, 61));
// text size in pixels
paint.setTextSize((int) (14 * scale));
// text shadow
paint.setShadowLayer(1f, 0f, 1f, Color.WHITE);
// set text width to canvas width minus 16dp padding
int textWidth = canvas.getWidth() - (int) (16 * scale);
// init StaticLayout for text
StaticLayout textLayout = new StaticLayout(
gText, paint, textWidth, Layout.Alignment.ALIGN_CENTER, 1.0f, 0.0f, false);
// get height of multiline text
int textHeight = textLayout.getHeight();
// get position of text's top left corner
float x = (bitmap.getWidth() - textWidth)/2;
float y = (bitmap.getHeight() - textHeight)/2;
// draw text to the Canvas center
canvas.save();
canvas.translate(x, y);
textLayout.draw(canvas);
canvas.restore();
return bitmap;
}
source : http://www.skoumal.net/en/android-drawing-multiline-text-on-bitmap/

You should handle it yourself, calculating the text size and wrapping the content in some way (break line at max width or wrap last word).
I already did it on Java SE with the FontMetrics, never for Android; but you should take a look:
http://developer.android.com/reference/android/graphics/Paint.FontMetrics.html
As pointed by Lisa, StaticLayout is the way to go to measure text wrapping.

android - adding a String over a Drawable image?

I'm trying to add a String to a Drawable image. I'm currently not using a Panel to draw and I'd like to keep it that way. Any ideas or do I need to invoke an onDraw() method?
My image is showing up with this code:
Drawable image = getResources().getDrawable(tile_types[tileType]);
setImageDrawable(image);
I'd like to add a String over this image.
Thanks.

Sam's answer was my starting point, but the image didn't show up, only the text (I use it on a Google Map). Finally I got it working with a LayerDrawable. Here is my solution:
private Drawable createMarkerIcon(Drawable backgroundImage, String text,
int width, int height) {
Bitmap canvasBitmap = Bitmap.createBitmap(width, height,
Bitmap.Config.ARGB_8888);
// Create a canvas, that will draw on to canvasBitmap.
Canvas imageCanvas = new Canvas(canvasBitmap);
// Set up the paint for use with our Canvas
Paint imagePaint = new Paint();
imagePaint.setTextAlign(Align.CENTER);
imagePaint.setTextSize(16f);
// Draw the image to our canvas
backgroundImage.draw(imageCanvas);
// Draw the text on top of our image
imageCanvas.drawText(text, width / 2, height / 2, imagePaint);
// Combine background and text to a LayerDrawable
LayerDrawable layerDrawable = new LayerDrawable(
new Drawable[]{backgroundImage, new BitmapDrawable(canvasBitmap)});
return layerDrawable;
}

Drawable image = getResources().getDrawable(tile_types[tileType]);
// Store our image size as a constant
final int IMAGE_WIDTH = image.getIntrinsicWidth();
final int IMAGE_HEIGHT = image.getIntrinsicHeight();
// You can also use Config.ARGB_4444 to conserve memory or ARGB_565 if
// you don't have any transparency.
Bitmap canvasBitmap = Bitmap.createBitmap(IMAGE_WIDTH,
IMAGE_HEIGHT,
Bitmap.Config.ARGB_8888);
// Create a canvas, that will draw on to canvasBitmap. canvasBitmap is
// currently blank.
Canvas imageCanvas = new Canvas(canvasBitmap);
// Set up the paint for use with our Canvas
Paint imagePaint = new Paint();
imagePaint.setTextAlign(Align.CENTER);
imagePaint.setTextSize(16f);
// Draw the image to our canvas
image.draw(imageCanvas);
// Draw the text on top of our image
imageCanvas.drawText("Sample Text",
IMAGE_WIDTH / 2,
IMAGE_HEIGHT / 2,
imagePaint);
// This is the final image that you can use
BitmapDrawable finalImage = new BitmapDrawable(canvasBitmap);

If your resulted text looks "angular" due to resizing, it's better to use TextPaint instead of plain Paint with these parameters:
TextPaint textPaint = new TextPaint(TextPaint.ANTI_ALIAS_FLAG | TextPaint.LINEAR_TEXT_FLAG);