objective-c - 如何管理 NSView 中自定义数据(不是照片)的绘制，该 NSView 的区域动态大于可视区域？

Question

更新:相对于下面的问题和答案，我似乎对 NSView 类与我试图绘制的自定义类有误解，包装NSScrollView。最后，我想要弄清楚的是如何在具有以下功能的 NSView 中管理自定义数据(不是照片)的动态绘制面积大于可视面积？

我不是在寻找讲义，但我是 Cocoa 的新手，我认为我正在根据 Apple 的文档进行最佳实践，但似乎我的基本原理是错误的。苹果的文档非常详细、技术性强，完全以照片处理为中心，因此对我来说毫无用处。 Apple 提供的相关代码示例(例如 Sketch)以典型的倾斜方式从打印机纸张尺寸中获取文档尺寸，但这不是我需要的。我在网上搜索了教程、示例等，但没有找到太多东西(我保证在解决这个问题后会写一个)。

我从 REALbasic 移植此代码，即使使用撤消命令，我也能完全工作，但这样做的范例完全不同。这对我来说并不是“点击”。我很感谢所提供的帮助，但我仍然缺少一些东西，感谢人们提供的任何其他内容。

谢谢

<小时/>

我有一个 NSView 子类，我正在其中创建一个钢琴卷帘 MIDI 接口(interface)。我正在尝试解决一些问题:

• 在滚动期间和之后绘制伪像
• 滚动期间和滚动后线条未跨越可见区域
• 滚动时(有时在 mouseDown 时)，水平滚动条会向右跳 1(一)个像素，但我还没有在任何地方实现scrollToPoint。

与上述相关的症状:

• 实现 adjustScroll 会使一切变得更糟。
• mouseDown 纠正了所有问题，除了有时向右跳转 1 像素的问题。
• 如果我取消 NSLog 命令的注释，则不会绘制任何内容。

Apple 的文档提到了像素精确绘图，但(当然)没有提供如何实现这一点的示例。我一直在使用 Floor() 函数来尝试获得一致的值，但是一旦我开始添加scrollToPoint 或任何其他复杂性，事情就会变得困惑。

请参阅链接图像作为示例。如果你相信的话，屏幕截图实际上清理了我在屏幕上看到的内容。几乎到处都有一半不透明度的双线。这同样适用于我绘制的任何对象。

Graphics Artifacts and inconsistencies in a subclassed NSView generated after scrolling http://www.oatmealandcoffee.com/external/NSViewArtifacts.png

这是代码。我讨厌公开放弃这么多，但我到处寻找线索，如果互联网有任何迹象，我是唯一有这个问题的人，我真的只想解决这个问题并继续前进。还有很多，而且还会有更多，但这些是我真正需要正确处理的核心内容，坦率地说，我不知道如何纠正它。

    - (void)drawRect:(NSRect)rect {
        //NSLog(@"OCEditorView:drawRect: START");

        [self setFrame:[[self EditorDocument] DocumentRect]];

        [[NSGraphicsContext currentContext] setShouldAntialias:NO];

        // CLEAR BACKGROUND

        [[[self EditorDocument] ColorWhiteKey] set];
        NSRectFill(rect);

        // BACKGROUND KEYS

        int firstRowLine = 0; //NSMinY(rect); //<- adding the function results in bad spacing on scrolling
        int currentRowLine = 0;
        int lastRowLine = NSMaxY(rect);

        //NSLog(@"lastRowLine:%d", lastRowLine);

        float currentZoomY = [self ZoomY];

        for (currentRowLine = firstRowLine; currentRowLine <= lastRowLine; currentRowLine += currentZoomY) {

            int currentTone = floor(currentRowLine / [self ZoomY]);
            BOOL isBlackKey = [[self MusicLib] IsBlackKey:currentTone];

            //NSLog(@"%d, tone:%d, black:%d", [self MusicLib], currentTone, isBlackKey);

            if (isBlackKey) {
                [[[self EditorDocument] ColorBlackKey] set];
            } else {
                [[NSColor whiteColor] set];
            }

            NSBezierPath *rowLine = [NSBezierPath bezierPath];

            NSPoint bottomLeftPoint = NSMakePoint(NSMinX(rect), currentRowLine);
            NSPoint bottomRightPoint = NSMakePoint(NSMaxX(rect), currentRowLine);
            NSPoint topRightPoint = NSMakePoint(NSMaxX(rect), currentRowLine + [self ZoomY]);
            NSPoint topLeftPoint = NSMakePoint(NSMinX(rect), currentRowLine + [self ZoomY]);

            [rowLine moveToPoint:bottomLeftPoint];
            [rowLine lineToPoint:bottomRightPoint];
            [rowLine lineToPoint:topRightPoint];
            [rowLine lineToPoint:topLeftPoint];

            [rowLine closePath];

            [rowLine fill];

            BOOL isOctave = [[self MusicLib] IsOctave:currentTone];
            if (isOctave) {
                [[[self EditorDocument] ColorXGrid] set];

                NSBezierPath *octaveLine = [NSBezierPath bezierPath];
                NSPoint leftPoint = NSMakePoint(NSMinX(rect), currentRowLine);
                NSPoint rightPoint = NSMakePoint(NSMaxX(rect), currentRowLine);
                [octaveLine moveToPoint:leftPoint];
                [octaveLine lineToPoint:rightPoint];
                [octaveLine stroke];
            }
        } 

        // BACKGROUND MEASURES

        //[[self EditorDocument].ColorYGrid setStroke];

        int firstColumnLine = 0;
        int currentColumnLine = 0;
        int lastColumnLine = NSMaxX(rect);

        int snapToValueInBeats = [[self EditorDocument] SnapToValue];
        int snapToValueInPixels = floor(snapToValueInBeats * [self ZoomX]);
        int measureUnitInBeats = floor([[self EditorDocument] TimeSignatureBeatsPerMeasure] * [[self EditorDocument] TimeSignatureBasicBeat]);
        int measureUnitInPixels = floor(measureUnitInBeats * [self ZoomX]);

        for (currentColumnLine = firstColumnLine; currentColumnLine <= lastColumnLine; currentColumnLine += snapToValueInPixels) {

            //int currentBeat = floor(currentColumnLine / [self ZoomX]);
            int isAMeasure = currentColumnLine % measureUnitInPixels;
            int isAtSnap = currentColumnLine % snapToValueInPixels;

            if ((isAMeasure == 0) || (isAtSnap == 0)) {

                if (isAtSnap == 0) { 
                    [[NSColor whiteColor] set];                 
                }

                if (isAMeasure == 0) { 
                    [[[self EditorDocument] ColorXGrid] set]; 
                }

                NSBezierPath *columnLine = [NSBezierPath bezierPath];

                NSPoint startPoint = NSMakePoint(currentColumnLine, NSMinY(rect));
                NSPoint endPoint = NSMakePoint(currentColumnLine, NSMaxY(rect));

                [columnLine moveToPoint:startPoint];
                [columnLine lineToPoint:endPoint];

                [columnLine setLineWidth:1.0];
                [columnLine stroke];

            } // isAMeasure or isAtSnap
         } // currentColumnLine

        // NOTES

        for (OCNoteObject *note in [[self EditorDocument] Notes]) {

            OCNoteObject *currentNote = note;

            NSRect noteBounds = [self GetRectFromNote:currentNote];
            //NSLog(@"noteBounds:%d", noteBounds);

            // set the color for the note fill
            // this will have to come from the parent Track

            NSMutableArray *trackColors = [self EditorDocument].TrackColors;

            if (note.Selected) {
                [[trackColors objectAtIndex:0] set];
            } else {
                [[trackColors objectAtIndex:1] set];
            }

            [NSBezierPath fillRect:noteBounds];

            // outline

            [[NSColor blackColor] set];
            [NSBezierPath strokeRect:noteBounds];

         } // for each note

        /*
        if (EditorController.startingUpApplication == YES) {
            [self setDefaultSettingForApplicationStartUp];
        }
         */
    //NSLog(@"OCEditorView:drawRect: END"); 
    }

- (void)mouseDown:(NSEvent *)theEvent {

    //NSLog(@"OCEditorObject:mouseDown: START");

    // This converts the click into coordinates
    MouseDownPoint = [self convertPoint:[theEvent locationInWindow] fromView:nil];

    // Calculate the beat and pitch clicked into...

    float startBeat = floor(MouseDownPoint.x / [self ZoomX]);
    float pitch = floor(MouseDownPoint.y / [self ZoomY]);
    float length = [[self EditorDocument] NewNoteLength];

    //NSLog(@"X:%f, Y:%f", MouseDownPoint.x, MouseDownPoint.y);
    //NSLog(@"beat:%f, pitch:%f", startBeat, pitch);

    LastDragPoint = MouseDownPoint; // save the point just in case.

    OCNoteObject *note = [self GetClickedNoteFromPoint:MouseDownPoint];

    if ([EditorController EditorMode] == AddObjectMode) {

        //NSLog(@"AddObjectMode)");

        float snapToX = [[self EditorDocument] SnapToValue];
        float snappedStartBeat = floor(startBeat / snapToX) * snapToX;

        //NSLog(@"%f = %f / %f * %f", snappedStartBeat, startBeat, snapToX, snapToX);

        OCNoteObject *newNote = [[self EditorDocument] CreateNote:snappedStartBeat Pitch:pitch Length:length];
        //NSLog(@"newNote:%d", newNote);

        [newNote Deselect];

    } else if ([EditorController EditorMode] == EditObjectMode) {

        //NSLog(@"EditObjectMode");

        // if nothing was clicked, then clear the selections
        // else if the shift key was pressed, add to the selection

        if (note == nil) {
            [self SelectNone];  
        } else {

            //NSLog(@"mouseDown note.pitch:%f, oldPitch:%f", note.Pitch, note.OldPitch);

            BOOL editingSelection = (([theEvent modifierFlags] & NSShiftKeyMask) ? YES : NO);
            if (editingSelection) {
                if (note.Selected) {
                    [self RemoveFromSelection:note];
                } else {
                    [self AddToSelection:note];
                }
            } else {
                if (note.Selected) {
                    // do nothing
                } else {
                    [self SelectNone];
                    [self AddToSelection:note];
                }
            }

            [self SetOldData];

        } // (note == nil)

    } else if ([EditorController EditorMode] == DeleteObjectMode) {

        if (note != nil) {
            [self RemoveFromSelection:note];
            [[self EditorDocument] DestroyNote:note];
        } // (note != nil)

    } // EditorMode

    [self setFrame:[[self EditorDocument] DocumentRect]];
    [self setNeedsDisplay:YES];
}

- (void)mouseDragged:(NSEvent *)theEvent {
    //NSLog(@"mouseDragged");

    NSPoint currentDragPoint = [self convertPoint:[theEvent locationInWindow] fromView:nil];
    // NSLog(@"currentDragPoint: %d", currentDragPoint)

    float snapToValueInBeats = [[self EditorDocument] SnapToValue];

    int deltaXinPixels = floor(currentDragPoint.x - MouseDownPoint.x);
    int deltaYinPixels = floor(currentDragPoint.y - MouseDownPoint.y);

    int deltaXinBeats = floor(deltaXinPixels / [self ZoomX]);
    int deltaY = floor(deltaYinPixels / [self ZoomY]);

    int deltaX = floor(deltaXinBeats / snapToValueInBeats) * snapToValueInBeats;

        for (OCNoteObject *note in [self Selection]) {
            [self MoveNote:note DeltaX:deltaX DeltaY:deltaY];       
        }

    LastDragPoint = currentDragPoint;

    [self autoscroll:theEvent];

    [self setNeedsDisplay:YES]; //artifacts are left if this is off.
}

- (void)mouseUp:(NSEvent *)theEvent {
    if ([EditorController EditorMode] == AddObjectMode) {

    } else if ([EditorController EditorMode] == EditObjectMode) {

    } else if ([EditorController EditorMode] == DeleteObjectMode) {

    }

    [self setNeedsDisplay:YES];
}

我很可能会遗漏一些明显的东西，但我认为我太接近代码了，无法看到它的解决方案。任何帮助是极大的赞赏!谢谢!

Answer 1

我认为您误解了 drawRect: 及其参数的工作方式:

当你的 View 或它的一部分需要重绘时，消息drawRect:由cocoa发送。 CGRect 参数是当前重绘的所有更新区域的边界框。这意味着您不应从该矩形导出 View 内对象的任何位置。它仅传递给方法以允许优化绘制:如果某些内容完全超出此矩形，则不需要重新绘制。

您应该根据 View 坐标系计算 View 内的所有位置:[selfbounds]。每次执行 drawRect: 时，它都不会改变，并为您提供 View 内容的原点和大小。

您的代码还有一些其他问题(例如，不要从 drawRect: 中调用 setFrame:)，但我认为您应该首先获取坐标正确，然后进一步研究如何计算矩形的像素对齐坐标。