如何在带有图标的自定义按钮中更改文本颜色？

Question

I'm new to Qt/QML and trying to create a custom button that has a label and an icon. I want to change the font to bold and the colour to some bright value since the button has a dark background. The problem is that as soon as I define label: Text , the icon would disappear. How can I redefine the label and still keep the icon?

import QtQuick 2.2
import QtQuick.Controls 1.1
import QtQuick.Controls.Styles 1.1

Item
{
    property alias text: btn.text;
    property alias iconSource: btn.iconSource;

    Button
    {
        id: btn;
        style: ButtonStyle
        {
            background: Rectangle
            {
                implicitWidth: 100;
                implicitHeight: 25;
                border.width: (control.activeFocus ? 2 : 1);
                border.color: "#888";
                radius: 8;
                gradient: Gradient
                {
                    GradientStop
                    {
                        position: 0;
                        color: (control.pressed ? "#929292" : "#424242")
                    }
                    GradientStop
                    {
                        position: 1;
                        color: (control.pressed ? "#818181" : "#313131")
                    }
                }
            }
            label: Text
            {
                text: control.text;
                // iconSource: btn.iconSource;
                font.bold: true;
                color: "#f2f2f2"
            }
        }
    }
}

Answer 1

You have to modify the ButtonStyle by copying and modifying the default built-in style:

/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the Qt Quick Controls module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
**     of its contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
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** $QT_END_LICENSE$
**
****************************************************************************/
import QtQuick 2.2
import QtQuick.Controls 1.2
import QtQuick.Controls.Private 1.0

/*!
    \qmltype ButtonStyle
    \inqmlmodule QtQuick.Controls.Styles
    \since 5.1
    \ingroup controlsstyling
    \brief Provides custom styling for Button

    You can create a custom button by replacing the "background" delegate
    of the ButtonStyle with a custom design.

    Example:
    \qml
    Button {
        text: "A button"
        style: ButtonStyle {
            background: Rectangle {
                implicitWidth: 100
                implicitHeight: 25
                border.width: control.activeFocus ? 2 : 1
                border.color: "#888"
                radius: 4
                gradient: Gradient {
                    GradientStop { position: 0 ; color: control.pressed ? "#ccc" : "#eee" }
                    GradientStop { position: 1 ; color: control.pressed ? "#aaa" : "#ccc" }
                }
            }
        }
    }
    \endqml
    If you need a custom label, you can replace the label item.
*/

Style {
    id: buttonstyle

    /*! The \l {QtQuick.Controls::}{Button} this style is attached to. */
    readonly property Button control: __control

    /*! The padding between the background and the label components. */
    padding {
        top: 4
        left: 4
        right: 4 + (control.menu !== null ? Math.round(TextSingleton.implicitHeight * 0.5) : 0)
        bottom: 4
    }

    /*! This defines the background of the button. */
    property Component background: Item {
        property bool down: control.pressed || (control.checkable && control.checked)
        implicitWidth: Math.round(TextSingleton.implicitHeight * 4.5)
        implicitHeight: Math.max(25, Math.round(TextSingleton.implicitHeight * 1.2))
        Rectangle {
            anchors.fill: parent
            anchors.bottomMargin: down ? 0 : -1
            color: "#10000000"
            radius: baserect.radius
        }
        Rectangle {
            id: baserect
            gradient: Gradient {
                GradientStop {color: down ? "#aaa" : "#fefefe" ; position: 0}
                GradientStop {color: down ? "#ccc" : "#e3e3e3" ; position: down ? 0.1: 1}
            }
            radius: TextSingleton.implicitHeight * 0.16
            anchors.fill: parent
            border.color: control.activeFocus ? "#47b" : "#999"
            Rectangle {
                anchors.fill: parent
                radius: parent.radius
                color: control.activeFocus ? "#47b" : "white"
                opacity: control.hovered || control.activeFocus ? 0.1 : 0
                Behavior on opacity {NumberAnimation{ duration: 100 }}
            }
        }
        Image {
            id: imageItem
            visible: control.menu !== null
            source: "images/arrow-down.png"
            anchors.verticalCenter: parent.verticalCenter
            anchors.right: parent.right
            anchors.rightMargin: 4
            opacity: control.enabled ? 0.6 : 0.5
        }
    }

    /*! This defines the label of the button.  */
    property Component label: Item {
        implicitWidth: row.implicitWidth
        implicitHeight: row.implicitHeight
        baselineOffset: row.y + text.y + text.baselineOffset
        Row {
            id: row
            anchors.centerIn: parent
            spacing: 2
            Image {
                source: control.iconSource
                anchors.verticalCenter: parent.verticalCenter
            }
            Text {
                id: text
                renderType: Settings.isMobile ? Text.QtRendering : Text.NativeRendering
                anchors.verticalCenter: parent.verticalCenter
                text: StyleHelpers.stylizeMnemonics(control.text)
                color: SystemPaletteSingleton.buttonText(control.enabled)
            }
        }
    }

    /*! \internal */
    property Component panel: Item {
        anchors.fill: parent
        implicitWidth: Math.max(labelLoader.implicitWidth + padding.left + padding.right, backgroundLoader.implicitWidth)
        implicitHeight: Math.max(labelLoader.implicitHeight + padding.top + padding.bottom, backgroundLoader.implicitHeight)
        baselineOffset: labelLoader.item ? padding.top + labelLoader.item.baselineOffset : 0

        Loader {
            id: backgroundLoader
            anchors.fill: parent
            sourceComponent: background
        }

        Loader {
            id: labelLoader
            sourceComponent: label
            anchors.fill: parent
            anchors.leftMargin: padding.left
            anchors.topMargin: padding.top
            anchors.rightMargin: padding.right
            anchors.bottomMargin: padding.bottom
        }
    }
}

Kind of annoying right? Also if you don't copy all that the alignment of the text will not be quite right.

However if all you want to do is change the colour and boldness of the text there is a simpler if somewhat ugly way:

    Button {
        text: "<font color=\"red\"><b>Hello</b></font>"
    }