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Open Source Technologies

Notes The basic function used to create a new image is called ImageCreate(). This function creates the
canvas area for your new image. For example to create an image that is 300px wide and 300px
high you would use following code:
1. $imageOne = ImageCreate(300, 300);

Now that you have canvis you need to define colours you want to use in it. Colours are defined
using RGB color system. Using decimal values from 0 to 255 for each of the red (R), green (G), and
blue(B) you can define a specific color. The function used to define colors is ImageColorAllocate().
The first color you allocate is used as the background color of the image.

1. $white = ImageColorAllocate($imageOne, 255, 255, 255);
2. $red = ImageColorAllocate($imageOne, 255, 0, 0);

3. $blue = ImageColorAllocate($imageOne, 0, 0, 255);
4. $green = ImageColorAllocate($imageOne, 0, 255, 0);

12.3.1 Drawing Lines and Shapes
There are several PHP functions to assist you in drawing lines and shapes. And as you can see
below the function names are very descriptive.
• ImageEllipse() — To draw an ellipse.
• ImageArc() — To draw arc (partial ellipse).

• ImagePolygon() — To draw a polygon.
• ImageRectangle() — To draw a rectangle.

• ImageLine() — To draw a line.
Each of these functions use x-axis and y-axis coordinates as indicators of where to start and stop
the drawing on the canvas. Here is sample of green rectangle that is 30px wide, 50px high and
10px from the left edge and 20px away from the top of the canvas.

1. Image Rectangle ($image One, 10, 20, 40, 70, $green);

As you can see drawing with PHP requires some planning ahead.
12.3.2 Using a Colour Fill

PHP can also fill the shapes with solid colour. Functions to do that are:
• ImageFilledEllipse() — To fill an ellipse.

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