255 lines
10 KiB
MQL5
255 lines
10 KiB
MQL5
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//+------------------------------------------------------------------+
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//| AI Canvas Scrollbar.mqh |
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//| Copyright 2026, Allan Munene Mutiiria. |
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//| https://t.me/Forex_Algo_Trader |
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//+------------------------------------------------------------------+
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#property copyright "Copyright 2026, Allan Munene Mutiiria."
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#property link "https://t.me/Forex_Algo_Trader"
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//--- Include guard
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#ifndef AI_CANVAS_SCROLLBAR_MQH
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#define AI_CANVAS_SCROLLBAR_MQH
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//--- Include required modules
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#include "AI Canvas Theme.mqh"
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#include "AI Canvas Primitives.mqh"
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//+------------------------------------------------------------------+
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//| Scrollbar State Structure |
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//+------------------------------------------------------------------+
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struct AiScrollState
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{
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int trackL; // Track left edge
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int trackT; // Track top edge
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int trackR; // Track right edge
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int trackB; // Track bottom edge
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int scrollPx; // Current scroll offset in pixels
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int viewportH; // Visible viewport height
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int totalH; // Total scrollable content height
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bool hoveredArea; // Cursor is inside the scrollbar area
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bool hoveredThumb; // Cursor is over the scrollbar thumb
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bool dragging; // Thumb is being dragged
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bool hover; // Generic hover flag
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int dragOriginPx; // Scroll position at drag start
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int dragOriginY; // Mouse Y at drag start
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};
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//+------------------------------------------------------------------+
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//| Reset scroll state to defaults |
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//+------------------------------------------------------------------+
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void AiScrollInit(AiScrollState &s)
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{
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//--- Zero track and scroll metrics
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s.trackL = 0; s.trackT = 0; s.trackR = 0; s.trackB = 0;
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s.scrollPx = 0;
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s.viewportH = 0;
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s.totalH = 0;
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//--- Clear hover and drag flags
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s.hoveredArea = false;
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s.hoveredThumb = false;
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s.hover = false;
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s.dragging = false;
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s.dragOriginPx = 0;
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s.dragOriginY = 0;
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}
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//+------------------------------------------------------------------+
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//| Compute maximum allowed scroll offset |
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//+------------------------------------------------------------------+
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int AiScrollMax(const AiScrollState &s)
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{
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//--- Cap minimum at zero when content fits in viewport
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int m = s.totalH - s.viewportH;
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return (m < 0) ? 0 : m;
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}
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//+------------------------------------------------------------------+
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//| Test if scrollbar should be visible |
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//+------------------------------------------------------------------+
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bool AiScrollVisible(const AiScrollState &s)
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{
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//--- Only visible when content overflows viewport
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return AiScrollMax(s) > 0;
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}
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//+------------------------------------------------------------------+
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//| Clamp scroll offset within valid range |
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//+------------------------------------------------------------------+
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void AiScrollClamp(AiScrollState &s)
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{
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//--- Clamp scroll position between 0 and max
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int m = AiScrollMax(s);
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if(s.scrollPx < 0) s.scrollPx = 0;
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if(s.scrollPx > m) s.scrollPx = m;
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}
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//+------------------------------------------------------------------+
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//| Compute thumb top and bottom Y coordinates |
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//+------------------------------------------------------------------+
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bool AiScrollThumbRect(const AiScrollState &s, int &thT, int &thB)
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{
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//--- Bail when scrollbar is not visible
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if(!AiScrollVisible(s)) { thT = 0; thB = 0; return false; }
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//--- Bail when track has no height
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int trackH = s.trackB - s.trackT;
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if(trackH <= 0) { thT = 0; thB = 0; return false; }
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//--- Size thumb proportional to viewport-to-content ratio
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int thumbH = (int)((double)trackH * (double)s.viewportH / (double)s.totalH);
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if(thumbH < 20) thumbH = 20;
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if(thumbH > trackH) thumbH = trackH;
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//--- Position thumb based on scroll ratio
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int maxScroll = AiScrollMax(s);
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int travel = trackH - thumbH;
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double ratio = (maxScroll == 0) ? 0.0 : (double)s.scrollPx / (double)maxScroll;
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thT = s.trackT + (int)((double)travel * ratio);
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thB = thT + thumbH;
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return true;
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}
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//+------------------------------------------------------------------+
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//| Test if point is over the scrollbar thumb |
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//+------------------------------------------------------------------+
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bool AiScrollHitTestThumb(const AiScrollState &s, int x, int y)
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{
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//--- Get thumb rect and test point
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int thT, thB;
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if(!AiScrollThumbRect(s, thT, thB)) return false;
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return AiPointInRect(x, y, s.trackL, thT, s.trackR - s.trackL, thB - thT);
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}
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//+------------------------------------------------------------------+
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//| Test if point is over the scrollbar area (track + padding) |
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//+------------------------------------------------------------------+
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bool AiScrollHitTestArea(const AiScrollState &s, int x, int y)
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{
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//--- Bail when scrollbar is not visible
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if(!AiScrollVisible(s)) return false;
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//--- Test against padded track for easier hover targeting
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const int pad = 6;
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return AiPointInRect(x, y, s.trackL - pad, s.trackT,
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(s.trackR - s.trackL) + 2 * pad, s.trackB - s.trackT);
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}
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//+------------------------------------------------------------------+
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//| Draw scrollbar thumb pill onto canvas |
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//+------------------------------------------------------------------+
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void AiScrollDraw(CCanvas &canvas, AiScrollState &s, CAiCanvasPrimitives &prim)
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{
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//--- Skip drawing when not hovered and not dragging
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if(!s.hoveredArea && !s.dragging) return;
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//--- Get thumb rect and bail if invalid
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int thT, thB;
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if(!AiScrollThumbRect(s, thT, thB)) return;
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const int sbW = s.trackR - s.trackL;
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const int thumbH = thB - thT;
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if(sbW <= 0 || thumbH <= 0) return;
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//--- Pick pill color and alpha by interaction state
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color pillCol;
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uchar pillA;
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if(s.dragging) { pillCol = g_ai_scrollSliderDrag; pillA = 255; }
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else if(s.hoveredThumb) { pillCol = g_ai_scrollSliderHover; pillA = 255; }
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else { pillCol = g_ai_scrollSlider; pillA = 180; }
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const uint pillArgb = ColorToARGB(pillCol, pillA);
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//--- Setup high-res super-sampling factor
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const int factor = 4;
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const int pws = sbW * factor;
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const int phs = thumbH * factor;
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//--- Reuse cached HR fill canvas from primitives helper
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if(!prim.EnsureHrFill(pws, phs)) return;
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prim.m_hrFill.FillRectangle(0, 0, pws - 1, phs - 1, 0);
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prim.FillRoundRectHR(prim.m_hrFill, 0, 0, pws, phs, MathMax(1, pws / 2), pillArgb);
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//--- Downsample HR pill back onto canvas with alpha blending
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const int ss2 = factor * factor;
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for(int py = 0; py < thumbH; py++)
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for(int px = 0; px < sbW; px++)
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{
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//--- Sum HR sub-pixels for this output pixel
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double sumA = 0, sumR = 0, sumG = 0, sumB = 0, wc = 0;
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for(int dy = 0; dy < factor; dy++)
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for(int dx = 0; dx < factor; dx++)
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{
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const int sx = px * factor + dx, sy = py * factor + dy;
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if(sx >= pws || sy >= phs) continue;
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const uint p = prim.m_hrFill.PixelGet(sx, sy);
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const uchar pa = (uchar)((p >> 24) & 0xFF);
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sumA += pa;
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if(pa > 0) { sumR += (p >> 16) & 0xFF; sumG += (p >> 8) & 0xFF; sumB += p & 0xFF; wc += 1.0; }
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}
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//--- Compute averaged final pixel and blend onto canvas
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const uchar fa = (uchar)(sumA / ss2);
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if(fa > 0 && wc > 0)
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prim.BlendPixelSet(canvas, s.trackL + px, thT + py,
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((uint)fa << 24) | ((uint)(uchar)(sumR / wc) << 16) |
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((uint)(uchar)(sumG / wc) << 8) | (uint)(uchar)(sumB / wc));
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}
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}
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//+------------------------------------------------------------------+
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//| Apply mouse-wheel scroll delta |
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//+------------------------------------------------------------------+
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void AiScrollByWheel(AiScrollState &s, int delta, int step = 30)
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{
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//--- Negative delta scrolls up, positive scrolls down
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if(delta > 0) s.scrollPx -= step;
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else s.scrollPx += step;
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AiScrollClamp(s);
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}
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//+------------------------------------------------------------------+
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//| Begin scrollbar thumb drag |
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//+------------------------------------------------------------------+
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void AiScrollBeginDrag(AiScrollState &s, int mouseY)
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{
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//--- Snapshot scroll position and mouse Y at drag start
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s.dragging = true;
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s.dragOriginPx = s.scrollPx;
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s.dragOriginY = mouseY;
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}
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//+------------------------------------------------------------------+
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//| Update scroll position during thumb drag |
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//+------------------------------------------------------------------+
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void AiScrollUpdateDrag(AiScrollState &s, int mouseY)
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{
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//--- Bail when not actively dragging
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if(!s.dragging) return;
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//--- Get thumb rect and bail when invalid
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int trackH = s.trackB - s.trackT;
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int thT, thB;
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if(!AiScrollThumbRect(s, thT, thB)) { s.dragging = false; return; }
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//--- Bail when no travel room
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int thumbH = thB - thT;
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int travel = trackH - thumbH;
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if(travel <= 0) return;
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//--- Compute new scroll position from mouse delta ratio
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int dy = mouseY - s.dragOriginY;
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double ratio = (double)dy / (double)travel;
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int maxScroll = AiScrollMax(s);
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s.scrollPx = s.dragOriginPx + (int)(ratio * maxScroll);
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AiScrollClamp(s);
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}
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//+------------------------------------------------------------------+
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//| End scrollbar thumb drag |
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//+------------------------------------------------------------------+
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void AiScrollEndDrag(AiScrollState &s)
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{
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//--- Clear drag flag
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s.dragging = false;
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}
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#endif // AI_CANVAS_SCROLLBAR_MQH
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