module fortplot_errorbar_rendering !! Errorbar rendering module !! !! Renders symmetric/asymmetric error bars for X/Y with optional caps. !! Draws using backend line primitives in data (transformed) space and !! respects current plot color. use, intrinsic :: iso_fortran_env, only: wp => real64 use fortplot_context use fortplot_scales, only: apply_scale_transform use fortplot_plot_data, only: plot_data_t use fortplot_constants, only: REFERENCE_DPI implicit none private public :: render_errorbar_plot contains subroutine render_errorbar_plot(backend, plot_data, xscale, yscale, symlog_threshold, & default_line_width, width, height, & margin_left, margin_right, margin_bottom, margin_top) !! Render error bars for a plot class(plot_context), intent(inout) :: backend type(plot_data_t), intent(in) :: plot_data character(len=*), intent(in) :: xscale, yscale real(wp), intent(in) :: symlog_threshold real(wp), intent(in), optional :: default_line_width integer, intent(in), optional :: width, height real(wp), intent(in), optional :: margin_left, margin_right real(wp), intent(in), optional :: margin_bottom, margin_top integer :: i, n real(wp) :: x_val, y_val real(wp) :: x_scaled, y_scaled real(wp) :: y_low, y_high, x_low, x_high real(wp) :: y_low_t, y_high_t, x_low_t, x_high_t real(wp) :: cap_half_x, cap_half_y real(wp) :: base_line_width, cap_line_width, restore_width if (.not. allocated(plot_data%x) .or. .not. allocated(plot_data%y)) return if (size(plot_data%x) == 0 .or. size(plot_data%y) == 0) return if (size(plot_data%x) /= size(plot_data%y)) return n = size(plot_data%x) ! Set color from plot_data to match markers/lines call backend%color(plot_data%color(1), plot_data%color(2), plot_data%color(3)) base_line_width = max(plot_data%elinewidth, 1.0e-6_wp) cap_line_width = base_line_width if (plot_data%capthick > 0.0_wp) cap_line_width = plot_data%capthick if (present(default_line_width)) then restore_width = max(default_line_width, 1.0e-6_wp) else restore_width = 1.0_wp end if call backend%set_line_width(base_line_width) ! Capsize is given in points (matplotlib convention). Convert the total ! cap length to data units per axis so the horizontal caps on Y error ! bars and the vertical caps on X error bars both render at the correct ! point size regardless of the data range or aspect ratio. call compute_cap_half_lengths(backend, plot_data%capsize, & width, height, margin_left, margin_right, & margin_bottom, margin_top, & cap_half_x, cap_half_y) do i = 1, n x_val = plot_data%x(i) y_val = plot_data%y(i) x_scaled = apply_scale_transform(x_val, xscale, symlog_threshold) y_scaled = apply_scale_transform(y_val, yscale, symlog_threshold) ! Y error bars (vertical) if (plot_data%has_yerr) then if (plot_data%asymmetric_yerr .and. allocated(plot_data%yerr_lower) & .and. allocated(plot_data%yerr_upper)) then y_low = y_val - plot_data%yerr_lower(i) y_high = y_val + plot_data%yerr_upper(i) else if (allocated(plot_data%yerr)) then y_low = y_val - plot_data%yerr(i) y_high = y_val + plot_data%yerr(i) else y_low = y_val y_high = y_val end if y_low_t = apply_scale_transform(y_low, yscale, symlog_threshold) y_high_t = apply_scale_transform(y_high, yscale, symlog_threshold) call backend%line(x_scaled, y_low_t, x_scaled, y_high_t) if (cap_half_x > 0.0_wp) then if (cap_line_width /= base_line_width) then call backend%set_line_width(cap_line_width) end if call backend%line(x_scaled - cap_half_x, y_low_t, & x_scaled + cap_half_x, y_low_t) call backend%line(x_scaled - cap_half_x, y_high_t, & x_scaled + cap_half_x, y_high_t) if (cap_line_width /= base_line_width) then call backend%set_line_width(base_line_width) end if end if end if ! X error bars (horizontal) if (plot_data%has_xerr) then if (plot_data%asymmetric_xerr .and. allocated(plot_data%xerr_lower) & .and. allocated(plot_data%xerr_upper)) then x_low = x_val - plot_data%xerr_lower(i) x_high = x_val + plot_data%xerr_upper(i) else if (allocated(plot_data%xerr)) then x_low = x_val - plot_data%xerr(i) x_high = x_val + plot_data%xerr(i) else x_low = x_val x_high = x_val end if x_low_t = apply_scale_transform(x_low, xscale, symlog_threshold) x_high_t = apply_scale_transform(x_high, xscale, symlog_threshold) call backend%line(x_low_t, y_scaled, x_high_t, y_scaled) if (cap_half_y > 0.0_wp) then if (cap_line_width /= base_line_width) then call backend%set_line_width(cap_line_width) end if call backend%line(x_low_t, y_scaled - cap_half_y, & x_low_t, y_scaled + cap_half_y) call backend%line(x_high_t, y_scaled - cap_half_y, & x_high_t, y_scaled + cap_half_y) if (cap_line_width /= base_line_width) then call backend%set_line_width(base_line_width) end if end if end if end do call backend%set_line_width(restore_width) end subroutine render_errorbar_plot subroutine compute_cap_half_lengths(backend, capsize, width, height, & margin_left, margin_right, & margin_bottom, margin_top, & cap_half_x, cap_half_y) !! Convert a point-valued capsize into per-axis half-lengths in data !! coordinates. Returns 0 when caps are disabled or sizing data is !! unavailable. capsize is the total cap length in points (matplotlib). class(plot_context), intent(in) :: backend real(wp), intent(in) :: capsize integer, intent(in), optional :: width, height real(wp), intent(in), optional :: margin_left, margin_right real(wp), intent(in), optional :: margin_bottom, margin_top real(wp), intent(out) :: cap_half_x, cap_half_y real(wp) :: plot_w_px, plot_h_px, cap_px real(wp) :: x_range, y_range cap_half_x = 0.0_wp cap_half_y = 0.0_wp if (capsize <= 0.0_wp) return if (.not. present(width) .or. .not. present(height)) return if (.not. present(margin_left) .or. .not. present(margin_right)) return if (.not. present(margin_bottom) .or. .not. present(margin_top)) return plot_w_px = real(width, wp) * (1.0_wp - margin_left - margin_right) plot_h_px = real(height, wp) * (1.0_wp - margin_bottom - margin_top) if (plot_w_px <= 0.0_wp .or. plot_h_px <= 0.0_wp) return ! Total cap length in pixels at the reference DPI, then half on each side. cap_px = capsize * REFERENCE_DPI / 72.0_wp x_range = abs(backend%x_max - backend%x_min) y_range = abs(backend%y_max - backend%y_min) if (x_range > 0.0_wp) cap_half_x = 0.5_wp * cap_px * x_range / plot_w_px if (y_range > 0.0_wp) cap_half_y = 0.5_wp * cap_px * y_range / plot_h_px end subroutine compute_cap_half_lengths end module fortplot_errorbar_rendering