#include "BrushPad.h"
#include <QPainter>
#include <QPaintEvent>
#include <QDebug>
BrushPad::BrushPad(QWidget *parent)
    : QGroupBox(parent)
{
    setMinimumSize(100, 100);
    m_canvas = QPixmap(size());
    m_canvas.fill(Qt::transparent);
}

void BrushPad::setBrushImage(const QImage &img)
{
    m_brush = img.convertToFormat(QImage::Format_ARGB32_Premultiplied);
}

void BrushPad::moveBrush(const QPoint &globalPos)
{
    // 1. 不管笔刷图，直接画一个 20×20 的红色方块到指定坐标
    QPainter p(&m_canvas);
    p.setCompositionMode(QPainter::CompositionMode_SourceOver);
    p.drawImage(globalPos, m_brush);   // 直接叠加，不清屏
    update();
}


void BrushPad::paintEvent(QPaintEvent *)
{
    // 让基类画边框/标题
    QGroupBox::paintEvent(nullptr);

    // 直接把我们自己的画布贴出来
    QPainter p(this);


    p.drawPixmap(contentsRect().topLeft(), m_canvas);
    // 这里 **绝对不要再调用 update()/repaint()**
}
void BrushPad::resizeEvent(QResizeEvent *)
{
    // 画布跟随控件大小
    QPixmap newPix(contentsRect().size());
    newPix.fill(Qt::transparent);
    QPainter p(&newPix);
    p.drawPixmap(0, 0, m_canvas);
    m_canvas = newPix;
}