imagefill()

(PHP 4, PHP 5, PHP 7)

区域填充

说明

imagefill()在$image图像的坐标$x，$y（图像左上角为 0, 0）处用$color颜色执行区域填充（即与 x, y 点颜色相同且相邻的点都会被填充）。

imagefill()例子

参见imagecolorallocate()。

Creating a new true-color image, filling it with a transparent color, and saving it as a PNG image can be accomplished with the following:

The image needs to be created with imagecreatetruecolor(), you must use imagefill() instead of imagefilledrectange(), and you need to call imagesavealpha(). No other combination of functions calls seems to produce the intended results.

Here is a function to generate a gradient.
You specify width, heigth and 4 colors (of the 4 corners).
An image handle of the gradient image will be returned.
You can copy the returned image onto another image using imageecopy.
This can be helpful if you want to generate a shadow for example.
("Glow effect example": Generate 8 gradients, one for each side and one for each corner. The outer side of the gradients have the background color and the inner sides have a bright color such as white.) 
But beware: This function is not optimized for performance, it might become slow on big images. For shadows, better cache the generated gradients.
Note: For gradients, using true-color is highly recommended. 

chess board 

is there any point to use $x and $y coordinates? They doesn't affect an output in any way. I can no make rectangular half filled with color. These params are useless.

If you need to fill a whole image (immediatly after its creation for instance), consider applying a filled rectangle instead, using imagefilledrectangle() :

which will require much less logic and processing from GD.

I feel its worth pointing out that you cannot fill a transparent colour that you have assigned with imagecolorallocatealpha, the colour will fill, but without its transparency,
I find the easiest method around this is to just fill a rectangle using imagefilledrectangle() to draw a fill instead.

I spend more then two hour to find a function that can fill a pattern or file as background instead of color. but i can't find. so i develop the following function. i though this function will save time who need it...
Function will get four parameter
1. Main Image Identifier
2. Pattern Image Identifier
3. Final Image Width
4. Final Image Height
If you set final image width or height is less then main image width or height then you may get wrong result

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