CODEWITHSUNDEEP
c#
Ernesto Ulloa
Ernesto Ulloa

Reputation: 482

How to completely cover an image with a transparent using C# Graphics.DrawImage

I'm triying to cover an image with another in order to provide a watermark but it has to cover the entire source image. The problem is that the watermark provided is of 600x600 and the source image can have any size and aspect ratio. So far it does not cover the source image entirely.

Upvotes: 0

Views: 189

Answers (1)

DotNet Developer
DotNet Developer

Reputation: 3018

I solved it like this (in a very straightforward way).

    private void button1_Click(object sender, EventArgs e)
    {
        var image = new Bitmap( this.pictureBox1.Image.Width, this.pictureBox1.Image.Height);
        var rect = new Rectangle(0, 0, this.pictureBox1.Image.Width, this.pictureBox1.Image.Height);

        Graphics graphics = Graphics.FromImage(image);
        graphics.DrawImage(this.pictureBox1.Image, 0, 0);

        var waterMarkImage = new Bitmap(this.pictureBox2.Image.Width, this.pictureBox2.Image.Height);
        for (int y = 0; y < waterMarkImage.Height; y++)
        {
            for (int x = 0; x < waterMarkImage.Width; x++)
            {
                var color = (this.pictureBox2.Image as Bitmap).GetPixel(x, y);
                color = Color.FromArgb(50, color.R, color.G, color.B);
                waterMarkImage.SetPixel(x, y, color);
            }
        }

        graphics.DrawImage(waterMarkImage, rect);

        this.pictureBox3.Image = image;
    }

In pictureBox1 I loaded main image. In pictureBox2 I loaded "water mark". In the event handler I created resulting image (first main image then the second) and loaded it into pictureBox3. To get water mark affect I reduced alpha component of color (I set it to 50).

Upvotes: 1

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