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QML别名:无法使用层找到id

qml qt

Antoine Morrier · 技术社区 · 6 年前

我正在尝试创建ShaderEffect的别名。但是,当我这样做时:

Item {
    id: root;
    property color colorBackground: Qt.rgba(0.9, 0.9, 0.9, 1.0);
    property color colorStroke: Qt.rgba(0.1, 0.1, 0.1, 1.0);
    layer.enabled: true;

    layer.effect: ShaderEffect {
        property alias colorBackground: root.colorBackground;
        property alias colorStroke: root.colorStroke;

        fragmentShader: "
            uniform lowp sampler2D source; // This item
            uniform lowp float qt_Opacity; // Inherited opacity of this item
            uniform lowp vec4 colorBackground;
            varying highp vec2 qt_TexCoord0;
            void main() {
                lowp vec4 p = texture2D(source, qt_TexCoord0);
                lowp float g = dot(p.xyz, vec3(0.344, 0.5, 0.156));
                gl_FragColor = colorBackground;
            }";
    }
}

Unable to find id root

当我这么做的时候:

Item {
    property alias colorBackground: shaderEffect.colorBackground;
    property alias colorStroke: shaderEffect.colorStroke;
    layer.enabled: true;

    layer.effect: ShaderEffect {
        id: shaderEffect;
        property color colorBackground: Qt.rgba(0.9, 0.9, 0.9, 1.0);
        property color colorStroke: Qt.rgba(0.1, 0.1, 0.1, 1.0);
        fragmentShader: "
            uniform lowp sampler2D source; // This item
            uniform lowp float qt_Opacity; // Inherited opacity of this item
            uniform lowp vec4 color;
            varying highp vec2 qt_TexCoord0;
            void main() {
                lowp vec4 p = texture2D(source, qt_TexCoord0);
                lowp float g = dot(p.xyz, vec3(0.344, 0.5, 0.156));
                gl_FragColor = color;
            }";
    }
}

我得到了同样的错误,但与shaderEffect。

如何解决这个问题?

2 回复 | 直到 6 年前

dtech 6 年前

layer.effect 真的期望 Component

由于没有具体的对象实例,因此没有 id

以及 alias

工作原理:

Item {
  id: root;
  property color colorBackground: Qt.rgba(0.9, 0.9, 0.9, 1.0);
  property color colorStroke: Qt.rgba(0.1, 0.1, 0.1, 1.0);
  layer.enabled: true;

  layer.effect: ShaderEffect {
    property color colorBackground: root.colorBackground;
    property color colorStroke: root.colorStroke;

    fragmentShader: "
            uniform lowp sampler2D source; // this item
            uniform lowp float qt_Opacity; // inherited opacity of this item
            uniform lowp vec4 colorBackground;
            varying highp vec2 qt_TexCoord0;
            void main() {
                lowp vec4 p = texture2D(source, qt_TexCoord0);
                lowp float g = dot(p.xyz, vec3(0.344, 0.5, 0.156));
                gl_FragColor = colorBackground;
            }";
  }
}

derM - not here for BOT dreams 6 年前

layer.effect is of type Component .

Components build their own scope root 仅通过动态作用域可用。

According to the documentation of property aliases:

它只能引用在声明别名的类型范围内的对象或对象的属性。

它不能引用在其类型范围之外声明的对象。

因此,它必须失败。