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[apps/shared] CurveView: implement drawArrow

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This commit is contained in:
Émilie Feral
2020-03-18 16:38:29 +01:00
parent 70335b7a47
commit 9e822e85e5
2 changed files with 66 additions and 0 deletions
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41
apps/shared/curve_view.cpp
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@@ -452,6 +452,47 @@ void CurveView::drawDot(KDContext * ctx, KDRect rect, float x, float y, KDColor
ctx->blendRectWithMask(dotRect, color, mask, workingBuffer);
}
void CurveView::drawArrow(KDContext * ctx, KDRect rect, float x, float y, float dx, float dy, KDColor color, KDCoordinate pixelArrowLength, float angle) const {
/* Let's call the following variables L and l:
*
* / |
* / |
* / l
* / |
* / |
* <--------------------------------------------------
* \
* \
* \
* \
* \
*
* ----- L -----
*
**/
assert(angle >= 0.0f);
/* We compute the arrow segments in pixels in order to correctly size the
* arrow without depending on the displayed range.
* Warning: the computed values are relative so we need to add/subtract the
* pixel position of 0s. */
float x0Pixel = floatToPixel(Axis::Horizontal, 0.0f);
float y0Pixel = floatToPixel(Axis::Vertical, 0.0f);
float dxPixel = floatToPixel(Axis::Horizontal, dx) - x0Pixel;
float dyPixel = y0Pixel - floatToPixel(Axis::Vertical, dy);
float dx2dy2 = std::sqrt(dxPixel*dxPixel+dyPixel*dyPixel);
float L = pixelArrowLength;
float l = angle*L;
float arrow1dx = pixelToFloat(Axis::Horizontal, x0Pixel + L*dxPixel/dx2dy2 + l*dyPixel/dx2dy2);
float arrow1dy = pixelToFloat(Axis::Vertical, y0Pixel - (L*dyPixel/dx2dy2 - l*dxPixel/dx2dy2));
drawSegment(ctx, rect, x, y, x - arrow1dx, y - arrow1dy, color, false);
float arrow2dx = pixelToFloat(Axis::Horizontal, x0Pixel + L*dxPixel/dx2dy2 - l*dyPixel/dx2dy2);
float arrow2dy = pixelToFloat(Axis::Vertical, y0Pixel - (L*dyPixel/dx2dy2 + l*dxPixel/dx2dy2));
drawSegment(ctx, rect, x, y, x - arrow2dx, y - arrow2dy, color, false);
}
void CurveView::drawGrid(KDContext * ctx, KDRect rect) const {
KDColor boldColor = Palette::GreyMiddle;
KDColor lightColor = Palette::GreyWhite;

25
apps/shared/curve_view.h
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@@ -75,6 +75,31 @@ protected:
Large
};
void drawDot(KDContext * ctx, KDRect rect, float x, float y, KDColor color, Size size = Size::Small) const;
/* 'drawArrow' draws the edge of an arrow pointing to (x,y) with the
* orientation (dx,dy).
* The parameters defining the shape of the arrow are the length in pixel of
* the projection of the arrow on the segment -'pixelArrowLength'- and the
* tangent of the angle between the segment and each wing of the arrow called
* 'angle'.
*
* / |
* / |
* / L
* / |
* / |
* <--------------------------------------------------
* \
* \
* \
* \
* \
*
* <--- pl --->
*
* pl = pixelArrowLength
* tan(angle) = L/pl
*/
void drawArrow(KDContext * ctx, KDRect rect, float x, float y, float dx, float dy, KDColor color, KDCoordinate pixelArrowLength = 10, float angle = 0.4f) const;
void drawGrid(KDContext * ctx, KDRect rect) const;
void drawAxes(KDContext * ctx, KDRect rect) const;
void drawAxis(KDContext * ctx, KDRect rect, Axis axis) const;