Interpolates colors

# Imagick::sparseColorImage

(PECL imagick 2 >= 2.3.0, PECL imagick 3)

Imagick::sparseColorImage — Interpolates colors

### 说明

public function Imagick::sparseColorImage(int `$SPARSE_METHOD`, array `$arguments`, int `$channel` = Imagick::CHANNEL_DEFAULT): bool

Given the arguments array containing numeric values this method interpolates the colors found at those coordinates across the whole image using `sparse_method`. 此方法在Imagick基于ImageMagick 6.4.5以上版本编译时可用。

### 参数

`SPARSE_METHOD`

  Refer to this list of sparse method constants

`arguments`

  An array containing the coordinates. The array is in format `array(1,1, 2,45)`

`channel`

  Provide any channel constant that is valid for your channel mode. To apply to more than one channel, combine channel constants using bitwise operators. 缺省为`Imagick::CHANNEL_DEFAULT`. 参考此 通道常数列表

### 返回值

成功时返回 `true`。

### 错误／异常

错误时抛出 ImagickException。

### 示例

示例 #1 SPARSECOLORMETHOD_BARYCENTRIC Imagick::sparseColorImage()

    <?php
        function renderImageBarycentric2() {
            $points = [
                [0.30, 0.10, 'red'],
                [0.10, 0.80, 'blue'],
                [0.70, 0.60, 'lime'],
                [0.80, 0.20, 'yellow'],
            ];
            $imagick = createGradientImage(
                400, 400,
                $points,
                \Imagick::SPARSECOLORMETHOD_BARYCENTRIC
            );
            header("Content-Type: image/png");
            echo $imagick->getImageBlob();
        }

    ?>

示例 #2 SPARSECOLORMETHOD_BILINEAR Imagick::sparseColorImage()

    <?php
        function renderImageBilinear() {
            $points = [[0.30, 0.10, 'red'], [0.10, 0.80, 'blue'], [0.70, 0.60, 'lime'], [0.80, 0.20, 'yellow'],];
            $imagick = createGradientImage(500, 500, $points, \Imagick::SPARSECOLORMETHOD_BILINEAR);
            header("Content-Type: image/png");
            echo $imagick->getImageBlob();
        }

    ?>

示例 #3 SPARSECOLORMETHOD_SPEPARDS Imagick::sparseColorImage()

    <?php
        function renderImageShepards() {
            $points = [
                [0.30, 0.10, 'red'],
                [0.10, 0.80, 'blue'],
                [0.70, 0.60, 'lime'],
                [0.80, 0.20, 'yellow'],
            ];
            $imagick = createGradientImage(600, 600, $points, \Imagick::SPARSECOLORMETHOD_SPEPARDS);
            header("Content-Type: image/png");
            echo $imagick->getImageBlob();
        }

    ?>

示例 #4 SPARSECOLORMETHOD_VORONOI Imagick::sparseColorImage()

    <?php
        function renderImageVoronoi() {
            $points = [
                [0.30, 0.10, 'red'],
                [0.10, 0.80, 'blue'],
                [0.70, 0.60, 'lime'],
                [0.80, 0.20, 'yellow'],
            ];
            $imagick = createGradientImage(500, 500, $points, \Imagick::SPARSECOLORMETHOD_VORONOI);
            header("Content-Type: image/png");
            echo $imagick->getImageBlob();
        }

    ?>

示例 #5 SPARSECOLORMETHOD_BARYCENTRIC Imagick::sparseColorImage()

    <?php
        function renderImageBarycentric() {
            $points = [
                [0, 0, 'skyblue'],
                [-1, 1, 'skyblue'],
                [1, 1, 'black'],
            ];
            $imagick = createGradientImage(600, 200, $points, \Imagick::SPARSECOLORMETHOD_BARYCENTRIC);
            header("Content-Type: image/png");
            echo $imagick->getImageBlob();
        }

    ?>

示例 #6 createGradientImage is used by other examples. Imagick::sparseColorImage()

    <?php
    function createGradientImage($width, $height, $colorPoints, $sparseMethod, $absolute = false) {

        $imagick = new \Imagick();
        $imagick->newImage($width, $height, "white");
        $imagick->setImageFormat("png");

        $barycentricPoints = array();

        foreach ($colorPoints as $colorPoint) {

            if ($absolute == true) {
                $barycentricPoints[] = $colorPoint[0];
                $barycentricPoints[] = $colorPoint[1];
            }
            else {
                $barycentricPoints[] = $colorPoint[0] * $width;
                $barycentricPoints[] = $colorPoint[1] * $height;
            }

            if (is_string($colorPoint[2])) {
                $imagickPixel = new \ImagickPixel($colorPoint[2]);
            }
            else if ($colorPoint[2] instanceof \ImagickPixel) {
                $imagickPixel = $colorPoint[2];
            }
            else{
                $errorMessage = sprintf(
                    "Value %s is neither a string nor an ImagickPixel class. Cannot use as a color.",
                    $colorPoint[2]
                );

                throw new \InvalidArgumentException(
                    $errorMessage
                );
            }

            $red = $imagickPixel->getColorValue(\Imagick::COLOR_RED);
            $green = $imagickPixel->getColorValue(\Imagick::COLOR_GREEN);
            $blue = $imagickPixel->getColorValue(\Imagick::COLOR_BLUE);
            $alpha = $imagickPixel->getColorValue(\Imagick::COLOR_ALPHA);

            $barycentricPoints[] = $red;
            $barycentricPoints[] = $green;
            $barycentricPoints[] = $blue;
            $barycentricPoints[] = $alpha;
        }

        $imagick->sparseColorImage($sparseMethod, $barycentricPoints);

        return $imagick;
    }

    ?>

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