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What is the correct way to horizontally add some spaced image into a Canvas?

I am absolutly new in Android development and I have the followind doubt.
I have to draw images one next to each other into a Canvas object.
So let to an example: I have this icon (it is pretty huge and I have to resize it):
So I have to put 3 of these icon one next to each other (adding some white space between an image and the next one).
So I have done something like this:
// Load the 2 images for the creation of the "difficulty graphic":
Bitmap chefHatOk = BitmapFactory.decodeResource(getResources(), R.drawable.chef_hat_ok);
// Where the previus image will be drawn:
Canvas canvas = new Canvas();
So I think that I can add the previous image to the Canvas doing something like this:
canvas.drawBitmap(smallImage, 0f, 0f, null);
I think that the first 0f value represent the horizontal space before the inserted image (the offset), correct me if I am doing wrong assertion.
So, how can I add 3 of these images one next to each other leaving some white space between an image and the next one?

Something like this should work:
Bitmap output = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(output);
int space = 10; // the space between images
for(int i = 0; i < 3; i++) {
canvas.drawBitmap(smallImage, i * (smallImage.getWidth() + space), 0, null);
}
// do whatever you want with output

This should do the work, eg for two image with space horizontal
public static mergeImages(Bitmap firstImage, Bitmap secondImage)
{
Bitmap cs;
int width, height;
float space = 60f; // space between image horizontal
if(firstImage.getWidth() > secondImage.getWidth()) {
width = firstImage.getWidth() + secondImage.getWidth();
} else {
width = s.getWidth() + secondImage.getWidth();
}
height = firstImage.getHeight();
cs = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
Canvas comboImage = new Canvas(cs);
comboImage.drawBitmap(firstImage, 0f, 0f, null);
comboImage.drawBitmap(secondImage, firstImage.getWidth()+space, 0f, null);
return cs; // result image
}

Draw a circle partially filled dynamically

I'm trying to play with canvas. I could draw some triangles and fill it partially drawing a path and paint it.I used Path, Points and Line. It was a great exercise to remember trigonometry. For now I would like to do the same with a circle, as you can see below. I want set a percentage and to fill this circle until the circle's height * percentage. How could me draw a circle like that with canvas or some lib?

You should think about it a little differently. The way I'd do it is to draw a coloured rectangle (where the height is a percentage of the circle's intended height) and then crop it with a circle. This answer explains how to crop an image in a circular shape (I'd rather link than retype the code here).

I finally got do it. I created two methods. As roarster suggested, I created a white rectangle as mask where the height is a percentage of the circle's intended height.
private Bitmap drawWithPorterDuff(Bitmap original, Bitmap mask, PorterDuff.Mode mode) {
Bitmap bitmap = Bitmap.createBitmap(original.getWidth(), original.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
Paint maskPaint = new Paint();
maskPaint.setAntiAlias(true);
canvas.drawBitmap(original, 0, 0, null);
maskPaint.setXfermode(new PorterDuffXfermode(mode));
canvas.drawBitmap(mask, 0, 0, maskPaint);
Bitmap edge = BitmapFactory.decodeResource(getResources(), R.drawable.edge);
maskPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.ADD));
canvas.drawBitmap(edge, 0, 0, maskPaint);
return bitmap;
}
public Bitmap createMask(int width, int height) {
Paint paint = new Paint();
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.WHITE);
paint.setAntiAlias(true);
Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
canvas.drawRect(0, 0, width, height, paint);
return bitmap;
}
At view's constructor I created a init() method with the folling code
PorterDuff.Mode mode = PorterDuff.Mode.SRC_IN;
Bitmap original = BitmapFactory.decodeResource(getResources(), R.drawable.blue_graph);
Bitmap mask = createMask(original.getWidth(), (int) ((original.getHeight()) * (1 - percentage)));
Bitmap result = drawWithPorterDuff(original, mask, mode);
imageView.setImageBitmap(result);

Add text with grey background to pictures like Snapchat does? Android/Java

Bitmap newBm = ...
Canvas canvas = new Canvas(newBm);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.WHITE);
paint.setTextSize((int) (44 * scale));
Rect bounds = new Rect();
paint.getTextBounds(gText, 0, gText.length(), bounds);
canvas.drawText(gText, x, y, paint);
I drew text on the Bitmap like so. How could I get a grey background that is the same height as the text but covers the whole screen??

You could use a Rect. Before drawing the text draw the Rect to the screen:
int screenWidth = getApplicationContext().getResources().getDisplayMetrics().widthPixels;
Rect greyBack = new Rect(0,top,screenWidth,bottom);
Paint paint = new Paint();
paint.setARGB(128, 100, 100, 100); //added alpha because Snapchat has translucent //grey background
canvas.drawRect(greyBack, paint);
top and bottom need to be coordinates above and below the text. You could use y's value and take away a bit for top and add a bit for bottom. How much you add/subtract is up to you and changes the height of the greyBack background.

The best way to see and learn how these sort of things are done with well written code is to look at the android source code itself. For example here is the onDraw method for a TextView it includes additional stuff you won't probably need like compoundPadding, but you can follow it through and get the basic concept of how it's done.

How can I scale my bitmap in Android based on the width and height pixels?

I want to be able to scale my image based on the screen size. In a normal java applet I would do something like the following....
int windowWidth = 1280;
int windowHeight = 720;
Image image;
public void paint(Graphics g)
{
g.drawImage(image, x, y, windowWidth / 4, windowHeight / 16, null);
}
I've been searching for an answer for a while and everything I find seems to turn up some weird result. From what I read I might need to do something with Resolution Independent Pixels but I'm not %100 sure.
The thing I am trying to avoid is having to create a whole new set of images and icons just for different screen densities. The method I showed above works for resizing desktop apps without a problem.
Edit:
This is what I have been using to draw an image in android.
Matrix matrix = new Matrix();
Bitmap image;
Constuctor....()
{
image = BitmapFactory.decodeResource(context.getResources(), R.drawable.play);
}
public void render(Canvas c)
{
c.drawBitmap(image, matrix, null);
}

Hi see thsi question I have posted scale bitmap
If you are using canvas get the width and height of the canvas. or if you want to have it formal normal layouts then get the width and height by using
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
dispWidth=metrics.widthPixels;
dispheight=metrics.heightPixels;
and then scale our bitmap according to your requirement like this. In this I Have to have 8 bricks so I have taken the width by dividing with the Number of columns
String strwidth=String.valueOf(((float)(bmp.getWidth())/NO_COLUMNS));
if(strwidth.contains("."))
{
scalebit=Bitmap.createScaledBitmap(bmp, (int)(Math.ceil(((float)bmp.getWidth())/NO_COLUMNS))*NO_COLUMNS, bmp.getHeight(), true);
}
else
{
scalebit=bmp;
}

Android rotate bitmap around center without resizing

I'm struggling to draw a rotating bitmap around its center and do the rotating without resizing the bitmap. I'm drawing all my sprites to the screen via a game thread, so I'm looking for a solution that incorporates the original bitmap and not the canvas.
Thanks in advance.
This is my code so far, it turns a bitmap around its center, yet resizes it.
i = i + 2;
transform.postRotate(i, Assets.scoresScreen_LevelStar.getWidth()/2, Assets.scoresScreen_LevelStar.getHeight()/2);
Bitmap resizedBitmap = Bitmap.createBitmap(Assets.scoresScreen_LevelStar, 0, 0, Assets.scoresScreen_LevelStar.getWidth(), Assets.scoresScreen_LevelStar.getHeight(), transform, true);
game.getGraphics().getCanvasGameScreen().drawBitmap(resizedBitmap, null, this.levelStar.getHolderPolygons().get(0), null);
Update:
I've noticed this isn't as easy as it sounds. My rotating code is not the problem. The bitmap rotates, yet the dst rect will also have to increase/decrease depending on the angle of rotation, or else the bimap will appear smaller, since it's drawn into a fixed dst rect.
So I'm guessing I'll have to develop some method that will return a dst rect.
So the methods needed to rotate a bitmap without appeared resizing:
public static Bitmap rotateBitmap(Bitmap bitmap, int rotation) // I've got this method working
and
public static Rect rotateRect(Rect currentDst, int rotation) // Don't got this
I understand this will require some math (trig), anyone up for the challenge? :P

You should draw the bitmap using the Matrix class. Below is a very basic idea assuming that you want to rotate an image inside of a "Ship" class. You update the current position Matrix inside the update method. In the onDraw() you draw the bitmap using the newly updated position Matrix. This will draw the rotated bitmap without resizing it.
public class Ship extends View {
private float x, y;
private int rotation;
private Matrix position;
private Bitmap bitmap;
...
#Override
public void onDraw(Canvas canvas) {
// Draw the Bitmap using the current position
canvas.drawBitmap(bitmap, position, null);
}
public void update() {
// Generate a new matrix based off of the current rotation and x and y coordinates.
Matrix m = new Matrix();
m.postRotate(rotation, bitmap.getWidth()/2, bitmap.getHeight()/2);
m.postTranslate(x, y);
// Set the current position to the updated rotation
position.set(m);
rotation += 2;
}
....
}
Hope that helps!
Also keep in mind that generating a new Bitmap object inside you game loop will be resource intensive.

This worked for me!
I created a method that returns a matrix. The matrix can be used in the following drawing method:
public void drawBitmap (Bitmap bitmap, Matrix matrix, Paint paint)
Here you go! (The parameter shape can be replaced with ease, if you would like that, just leave a comment):
public static Matrix rotateMatrix(Bitmap bitmap, Shape shape, int rotation) {
float scaleWidth = ((float) shape.getWidth()) / bitmap.getWidth();
float scaleHeight = ((float) shape.getHeight()) / bitmap.getHeight();
Matrix rotateMatrix = new Matrix();
rotateMatrix.postScale(scaleWidth, scaleHeight);
rotateMatrix.postRotate(rotation, shape.getWidth()/2, shape.getHeight()/2);
rotateMatrix.postTranslate(shape.getX(), shape.getY());
return rotateMatrix;
}
NB: If you want an animated rotation, the rotation parameter will have to be updated with new values every frame eg. 1 then 2 then 3 ...