This repository is an article-derived reference project based on the original MQL5 article. It does not claim to reproduce the full original source code unless files are explicitly attached.
## Overview
This project references MQL5 article **Part 32** of a Tools Palette series. The article extends a previously built interactive chart sidebar with a dedicated crosshair subsystem that adds:
- reticle tick-mark overlays
- full-chart vertical and horizontal crosshair lines
- dynamic price and time axis labels
- a circular magnifier lens for zoomed candle inspection
- a double-click measurement mode with anchor, diagonal line, bar count, pip distance, and raw price difference
The implementation described in the article is centered around canvas-based rendering and chart event handling.
## Original Article
- **Article ID:** 22233
- **Author:** Allan Munene Mutiiria
- **Publication date:** 2026.05.21
- **Category:** MQL5 GUI / Chart objects
- **URL:** https://www.mql5.com/en/articles/22233
## Repository Purpose
This repository should be treated as a **reference/reconstruction project** for the article<6C>s described architecture and code fragments.
Its purpose is to document and preserve the article<6C>s main implementation ideas for:
- custom chart navigation overlays in MQL5
- layered bitmap-label canvas rendering
- magnifier lens rendering on live chart data
- measurement tooling integrated into a sidebar-driven UI
- event-driven crosshair interaction and cleanup logic
## Key Concepts
- Custom crosshair rendering beyond the default MetaTrader crosshair
- Reticle overlay with configurable offset, tick length, and thickness
- Magnifier lens with configurable diameter, zoom factor, and cursor offset
- Axis label rendering using chart foreground/background colors
- Canvas layer expansion from basic sidebar/flyout rendering to multiple overlay surfaces
- Bresenham line drawing for measure diagonals
- Double-click detection using microsecond timing
- Conversion between chart coordinates and screen coordinates
- Theme-aware redraw behavior
- Automatic hiding of crosshair elements over sidebar and flyout regions
## Algorithm / Architecture Summary
The article describes the following architecture:
1.**New input parameters**
-`ReticleOffset`
-`ReticleTickLen`
-`ReticleThickness`
-`MagDiameter`
-`MagZoom`
-`MagOffset`
-`AxisLabelFontSize`
-`AxisLabelFont`
2.**Primitive extension**
-`CCanvasPrimitives` is extended with `DrawBresenhamLine(...)` for pixel-level diagonal rendering with alpha blending.
3.**Canvas layer expansion**
-`CCanvasLayer` grows from four canvases to fifteen total surfaces.
- Added canvases include reticle, magnifier, crosshair lines, crosshair labels, measure anchor lines, measure labels, and a full-screen diagonal line canvas.
- Helper methods prefill 1-pixel-wide or 1-pixel-tall line canvases using chart foreground colors.
4.**Dedicated manager class**
- A new `CCrosshairManager` class is introduced between sidebar rendering and chart event handling.
- It tracks visibility flags, measurement state, anchor coordinates, double-click timing, and cached magnifier cursor position.
5.**Rendering responsibilities**
- Draw reticle tick marks on a transparent square canvas.
- Show/hide and reposition vertical/horizontal crosshair lines.
- Render and place price/time axis labels.
- Render a circular magnifier lens with:
- candle bodies and wicks
- bid/ask lines
- circular clipping
- anti-aliased lens border
- center guide marks
- current price label
6.**Measurement mode**
- Double-click toggles measurement anchor mode.
- Anchor time/price and pixel coordinates are stored.
- Vertical/horizontal anchor lines and axis labels are shown.
- A diagonal line is drawn from anchor to current cursor.
- A floating chart label shows bars, pips, and absolute price difference.
7.**Top-level integration**
- Cleanup method removes crosshair and measurement state on tool switch.
- Mouse-move handler coordinates all real-time updates when the crosshair tool is active.
## Mentioned or Attached Files
### Explicitly attached files
No attached source files were available in the processed input.
### Files mentioned in the article text
-`Tools Palette Part 4.mq5`
### Classes mentioned in the article
-`CCanvasPrimitives`
-`CCanvasLayer`
-`CCrosshairManager`
-`CToolsSidebar`
### Methods specifically shown or discussed
-`DrawBresenhamLine`
-`CreateAllCanvases`
-`DestroyAllCanvases`
-`DrawCrossVerticalLinePixels`
-`DrawCrossHorizontalLinePixels`
-`DrawMeasureVerticalLinePixels`
-`DrawMeasureHorizontalLinePixels`
-`DrawReticleTickMarks`
-`ShowReticle`
-`HideReticle`
-`UpdateReticlePosition`
-`ShowCrossVertical`
-`HideCrossVertical`
-`UpdateCrossVerticalPosition`
-`ShowCrossHorizontal`
-`HideCrossHorizontal`
-`UpdateCrossHorizontalPosition`
-`ShowCrossPriceLabel`
-`HideCrossPriceLabel`
-`ShowCrossTimeLabel`
-`HideCrossTimeLabel`
-`DrawAndPositionAxisLabel`
-`UpdateCrosshairAxisLabels`
-`ShowMeasureLines`
-`HideMeasureLines`
-`UpdateMeasureVerticalPosition`
-`UpdateMeasureHorizontalPosition`
-`UpdateMeasureAnchorLabels`
-`ShowMagnifier`
-`HideMagnifier`
-`UpdateMagnifierPosition`
-`DrawMagnifierLensContent`
-`UpdateMeasureDiagonalLine`
-`UpdateMeasurementInfoLabel`
-`HideAllCrosshairElements`
-`ShowAllCrosshairElements`
-`HandleCrosshairDoubleClick`
-`DeleteAllMeasureObjects`
-`CleanupCrosshairOnToolSwitch`
-`HandleCrosshairMouseMove`
## Statistics
- **Inputs added:** 8
- **New canvas layers added:** 11
- **Total canvases after expansion:** 15
- **New manager class introduced:** 1
- **Protected member variables in `CCrosshairManager` described by the article:** 20
- **Protected methods in `CCrosshairManager` declared in the article:** 30
- The full original project source code is **not available** in the provided input.
- Only article text and embedded code excerpts were provided, so this repository should not be presented as a complete drop-in reproduction.
- The article depends on earlier parts of the Tools Palette series, especially prior sidebar, renderer, event-routing, and tool-registry infrastructure.
- Some referenced base classes and existing methods are not fully included in the provided material.
- Backtesting visuals are described, but no packaged test assets or complete runnable project structure were attached in the processed input.
