Painting in other UI frameworks

SharpCell.Grid holds everything about the grid that is not Avalonia or WPF: sizes and positions, hit testing, selection, copying, scrolling and painting. The two SpreadsheetView controls are thin hosts over it, and a host for another UI framework is the same few calls.

var painter = new GridPainter
{
    // Text width in your UI framework's font engine, for fitting numbers and running text.
    MeasureText = (text, font) => text.Length * font.Size * 0.5,
};
painter.Layout = SheetLayout.FromWorksheet(sheet, painter.MaxDigitWidth(sheet));
painter.FrozenRows = sheet.FrozenRows;
painter.FrozenColumns = sheet.FrozenColumns;

var viewport = new GridViewport(OffsetX: 0, OffsetY: 0, Width: 800, Height: 600);
var selection = GridSelection.Cell(new CellPosition(1, 1), sheet);
painter.Paint(canvas, sheet, viewport, selection);   // canvas: your IGridCanvas

// A click, then a drag to (300, 90): what Excel selects, and what is copied.
if (painter.Hit(viewport, x: 120, y: 30, sheet) is { } hit)
    selection = GridSelection.At(hit, sheet).ExtendTo(painter.CellNearest(viewport, 300, 90), sheet);
string copied = GridClipboard.Text(sheet, selection.Area);

The parts

• SheetLayout holds the column widths and row heights in pixels, their offsets, the cell under an offset and the cells in a rectangle. SheetLayout.FromWorksheet converts a sheet's sizes as Excel does, from the width of the widest digit of the default font.
• GridViewport is what is shown: the scroll offset into the sheet and the size of the grid on screen, headers included.
• GridPainter paints the part of the sheet in a viewport and the selection onto an IGridCanvas, and answers where a cell is (CellBounds), what is under a point (HitTest for cells, Hit for headers and the corner too), which cell a drag has reached (CellNearest, past the edges the next one out of view), and where to scroll (ScrollIntoView, Clamp).
• GridSelection is Excel's selection: what a click selects (At), and each step of the mouse and keyboard (ExtendTo, Extend, Move, MoveWithin, EntireColumns, EntireRows). A host maps its input events to these calls; SpreadsheetView shows how.
• GridEditor changes cells as Excel does when people edit them, typing (Enter, through SharpCell's Cell.Input), Delete (Clear) and pasting text (Paste), each change one step to Undo and Redo, the workbook recalculated after it.
• GridClipboard gives the selected cells as text and as HTML, the forms Excel pastes, and WindowsHtml wraps the HTML in the clipboard format Windows applications read.
• IGridCanvas is what a host implements over its drawing API: fill and stroke rectangles, draw lines with a dash pattern, draw text inside bounds, cut off at them, on one line or wrapped.

Measuring text

GridPainter.MeasureText gives the width of text in a font, from the host's font engine. With it, numbers are fitted to their column, text runs on over empty cells, and row headers widen for long row numbers. Without it, nothing is fitted and Calibri 11's digit width (7 pixels) is assumed.

GridFont sizes are in device-independent pixels: 11 points are 14.67 pixels at 96 DPI. GridPainter.FontOf converts a SharpCell font.