java - 调色板算法输出从红色到蓝色的颜色网格

Question

如你所见http://www.rapidtables.com/web/color/RGB_Color.htm颜色按照算法模式从红色变为蓝色，从深色变为白色。您将如何在基本循环中编写代码？我正在为 JavaFX 培训做这个!

这是我目前使用随机颜色的基本结构，应该用算法代替:

    for(int x = 0;x<12;x++) {
        for(int y = 0; y< 10; y++) {
            Random random = new Random();
            int r = random.nextInt(256);
            int g = random.nextInt(256);
            int b = random.nextInt(256);

            Label label = new Label();
            label.setPrefSize(30,30);
            label.setStyle("-fx-background-color: rgb(" + r + "," + g + "," + b + ")");
            colorPane.add(label, x,y);
        }
    }

Answer 1

请注意，我建议使用 Rectangle 而不是 Label。

另外 hsb 值似乎更合适:

• 每一列都有相同的色调
• 前半列亮度增加，但饱和度保持在1
• 该列的后半部分亮度保持为 1，但饱和度从 1 降低到 0

最后一列是个异常(exception)，因为它只显示亮度增加的灰度。

以下代码允许您创建调色板(或至少足够接近):

@Override
public void start(Stage primaryStage) {
    GridPane gridPane = new GridPane();
    gridPane.setHgap(4);
    gridPane.setVgap(4);

    final int columns = 12;
    final int rows = 10;
    final int fullBrightness = (rows - 1) / 2;
    final int columnCount = columns - 1;

    // fill upper half with full saturation but increasing brightness
    for (int y = 0; y <= fullBrightness; y++) {
        double brightness = y / (double) fullBrightness;
        for (int x = 0; x < columnCount; x++) {
            Rectangle rect = new Rectangle(15, 15, Color.hsb(x * (360d / (columns - 1)), 1, brightness));
            rect.setStroke(Color.BLACK);
            gridPane.add(rect, x, y);
        }
    }

    // fill lower half with full brightness but decreasing saturation
    for (int y = fullBrightness + 1; y < rows; y++) {
        double saturation = 1 - ((double) (y - fullBrightness)) / (columns - 1 - fullBrightness);
        for (int x = 0; x < columnCount; x++) {
            Rectangle rect = new Rectangle(15, 15, Color.hsb(x * (360d / (columns - 1)), saturation, 1));
            rect.setStroke(Color.BLACK);
            gridPane.add(rect, x, y);
        }
    }

    // fill last column with grayscale
    for (int y = 0, maxIndex = rows - 1; y < rows; y++) {
        Rectangle rect = new Rectangle(15, 15, Color.hsb(0, 0, y / (double) maxIndex));
        rect.setStroke(Color.BLACK);
        gridPane.add(rect, columnCount, y);
    }

    Scene scene = new Scene(gridPane);

    primaryStage.setScene(scene);
    primaryStage.show();
}